Sure with a little work. You'll need the fuel lines and pumps from your 242. Not sure if your 142 has an in-tank pump or not (see my previous post requesting info on what sort of 140 your working on). If you have a carb'ed car then you'll need an in-tank pump to feed the main pump and you'll need to plumb in a return line.
Take the fuel filter and bracket from the 242 and figure out where to mount it on a 140 (look for a few pics from the web...
POW)

See where he's stashing the fuel filter?
I'm assuming at this point that you've removed the drive train from the 242 and have it sitting beside you...complete with wiring harness etc. Take the rad and hoses etc. Note that the pic shows a not so brilliant location for the ignition box - you'll do better.
Then get your Green Manual or Haynes out and figure out how to convert the 140 main engine harness to fit up to the 242 engine harness (there isn't much there - but we don't want to do this ghetto style do we?). Then with the fuel and the wiring sorted, put the B23E into it's new home and transfer things like the air filter and hook up the exhaust. I'm not sure what parts of the drive line will swap over as I don't know if the 140 got the Dana 30 (I think it did), so take the drive shaft off your 242 and swap it to your 140 (hope the centre bearing has somewhere to go - probably fits). Change the u-joints while the drive shaft is on your floor.
Hook up the speedo and you're good to go.
Re my performance comments, these cars weigh around 3000 lbs and motivating them with 140 hp is the performance equivalent of a kick in the nads. It won't shove you into your seat like a turbo car with 40 more ponies will and it will need revs to make power. For 1981, getting that sort of power out of a 4 banger was pretty respectable (in league with small V8's of the time) - but lets not kid ourselves here, it isn't a muscle car or a particularly sporty car (that doesn't mean it isn't cool) and I'm not being a downer. I'm just saying that for the trouble, doing a turbo swap into a 140 (see above) is more fun per hour spent.
Craig