porkface wrote--"the olds 215 is intriguing". I was originally going to put the V8 into a nice rust free '74 MGB-GT (ala Costello and factory built Rover powered GT V8's) but instead repaired the MG motor and drove the OD equipped car for a couple of years. As repairing 240 series cars was a main part of my work it was a natural to look to one as a home for the engine (base 2bbl 155hp-210ft-lbs torque). A '76 265 came along with the usual V6 maladies--cams, rockers and timing chain. In went the 215 and Olds Roto-Hydramatic--way lighter than the V6 and BW55. We put about 150k miles on that version. One of the things I love about my conversion is that when you look underneath you see a B18/20 oil pan (relocated the oil pickup and welded the bottom half of the Volvo pan to the Olds flange) to fit in the engine bay with the V8 set way back. It drove real nice too--handling and brakes totally Volvo like (215 weighs less than the B21/23/230 as well). The new version is hooked to a Camaro T5 gearbox---all the fiddly things need to be finished out now--project's been stalled for quite some time.
The larger Rover versions have some problems pulling head studs out but I think the 3.9 would be reliable. I love the motor--great racing history, likes to rev, very smooth. I could go on and on--but wont -- Dave