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IBS includes a whole heap of parts to properly intercool a non-IC 240. A dealer intercooler car would have everything a factory IC car would (if done correctly....some dealers omitted parts that are really bitchy to install *caugh* sleeve in the k-jet boot *caugh*) minus the million pound stepped flywheel in stick shift cars and the different style anti-tamper shield over the mixture screw on the fuel dist.
When someone mentions IBS, I usually think of the RPM relay+ boost (pressure) bleed solenoid arrangement intercooled 240Ts came with to crank the boost up to 10.5psi above 3750rpm. I'm not sure what the original intent of that thing was....whether it was to make the power band feel smoother and more N/A like (since non-IC 240Ts make pretty smooth (if only a little) power) or whether it was to keep the things from pinging badly in the midrange on nasty regular gas. I can say that it works pretty nicely for the latter use on a car running 17-18psi normally on stock k-jet and turbo and everything and then cranking it up to 21-22 above 3750.
As far as heads go, you can probably find a less warped less stressed cylinder head on an N/A car. Old crusty non-IC 240Ts especially need exhaust valve guides on #3 more than any other SOHC volvo I've found. I have a small coolant passage turbo '85 SCP 398 K-jet head that I completely rebuilt sitting on the shelf as a spare. It is only shimmed up for the T-cam that is in it. I don't think SCP is that big of a deal on a B21 really. I like SCP on a B23 bore, but Matt didn't break his and I haven't ever blown an HG and have railed on my boosted volvos (and volvos in general) like a savage. Heads are about $35 in the boneyard here. I'm usually tripping over k-jet heads, though you want to make sure you find the best starting place you can...an unmolested unwarped one that had good oil and didn't get too hot. The latter is probably not too hard to find in canada. Lots of overheats start showing up in about may when all the plugged up rads and cooling system parts that start to leak or burst or otherwise let the car overheat from the season change starting showing up and test things.
More likely than not you can find a low mile low stress head for cheap and freshen it up. If they had good oil and didn't overheat, guides are seldom necessary. I consider it completely legit to shave the head a bit, lap the valves in, check the guides and cam shaft clearance and put a head back on a car for about $100 all into the project. On my 244ti police car, I shaved the head a bit more to bring the SCR up a bit (after completely rebuilding it after 260K miles (the car ran totally fine) (and to push the envelope a bit for "safe" head shaving), ported it a bit, added a cometic HG, converted it to a B230 manifold, updated the breather box, put diesel grade vac hoses on it, cleaned all of the K-jet, and did the wiring harness with a nearly new updated volvo one I found in the JY and put it all back together clean and pretty. That way I ended up doing the least amount of work twice and shouldn't have to go in there again for a good long time. The result is a car that runs lots of boost reliably on stock parts on pump gas.
While I had the head off, I also replaced all the exhaust studs with new parts from volvo and thread serted the far holes on the head (they like to pull away faster than the others with the 240T exhaust manifold), checked the exhaust mani for flat and ground it myself, replaced the alt voltage regulator and checked the bearings and diodes, replaced the accessory bushings in the alt and PS, did all the front seals in such a way that they wouldn't leak, replaced the oil cooler thermostat and o-ring and used a late model oil cooler, cleaned the hell out of everything, checked the date on the heater control valve, checked the waterpump age, brand and condition, and replaced all the heater and rad hoses with new OEM stuff, and soaked the pistons in lots and lots of chemtool. The engine bay is cramped enough with enough old worn out stressed junk on in a 240T that I'd try to knock out all that stuff so you don't have to touch it for a while and don't do work twice. It is also not much more money or time with the head off, but takes a ton more of your time to do with the head installed. I also consider the ATP v-band wastegate housing something I'd never go without on a garrett turbo volvo that I use as a personal car anymore...better performance and dropping the whole downpipe is one stainless nut on a band clamp is a wonderful thing. The engine bay isn't as pretty as i'd like, but that makes for a pretty fun reliable K-jet B21FT powered winter beater.
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