Stock B20's varied from aroun 100 - 130 hp - with the B20E being the highest rated engines as stock. Fuel injected engines have slightly better cams and slightly bigger intake valves to their credit - the 'E' has a high CR as well.

With modifications 150 is pretty easy to get, each HP onwards up to about 200 (or so) will cost incrementally more and more (mainly intake, head, exhaust, although big bore bottom end rebuilds are possible for ~200 more cc's). Or go the supercharger route (John Parker's kit) and skip most of the fiddly little improvements in favor of the one big one for probably 250 hp or so (with lots of tuning and a low CR engine).

In any case the PV is lighter than any other Volvo at 2250 lbs. An warmed up Volvo engine will feel better in it than in any other Volvo. Some bigger wheels (6 inch wheels, 215/50 rubber), suspension improvements (IPD sways, Bilstein shocks), and some gearing improvements (either an OD tranny or a lower numeric rear end) and you'll have a neat old car.