OP you'll have to really love it to justify the effort in getting that PRV six to be something interesting. Other options are readily available that go like hell. LS comes to mind. The B-27 is an all aluminum engine that got a LOT better as the Frenchies figured it out. That said... A fellow could find that Eagle Premier/Dodge Monaco from '89-'91, pull the motor complete with engine management.... Sort out what wiring stays, what goes... Replace lower engine case of EP/DM engine (everything below the centerline of the crankshaft + timing cover) and accessory drive with what is in the Volvo or even adapt the EP accessory drive for an even more colorful collection of bits. Use the trigger wheel of the EP (odd 120 degree thing)... Give it a B-280 throttle elbow with Four valve Volvo straight six from 960 throttle body + about a hundred details that get solved along the way. for a 150-160 horse smooth runner. Sounds like a lot of work? It is. I did this and enjoyed it for a few years. I've also used the EP block with Odd-firing heads on it... EP/DM Cams and hydraulic rocker arms (have to whittle off the distributor drive gear from your B-27 and hang it on the even-firing cam. Smooth runner that looks stock.
The engine in the rallycar is standard 93X73 bore & stroke. Volvo B-280 Block with Eagle Premier liners (93mm), and EP 'E' heads for the best intake port... turbo ect ect. Yes, goes like hell. Broke everything 'unbreakable' in Volvo drivetrain. Yup. JVL was involved with internals for that one. Started as a set of forged pistons on stock rods as JVL believed those stock rods to be "plenty beefy" which resulted in holes in a block top, sides and bottom when one of those rods broke. The rest of the stock rods in that engine measured out 1-3mm shorter then when installed. If you are going to go to the effort of getting in one give it forged pistons and H-Beam rods just as we do for every other engine we want to be strong. JVL Scared up a used Jerico trans and Quarter Master three disc clutch too. He is good at finding others used junk. Bill Scribner in Kent made up the bellhousing and the 9" Ford rear end after breaking too many Volvo axles and wheel studs (five studs... All at once) to count. Dave Clark did the Jerico install including modify trans tunnel for external trans linkage. JVL also pushed for installing GP-A Escort Cosworth 4X4 front suspension that "Is good enough for World Rally" that made for a horrible crash due to yet another of his half-baked engineering solutions. Could have had Sellholm's package of front suspension and brakes and been winning events for what I ended up with into JVL's solution that didn't work for sh!t. Again.
I've done a couple of stroked even-firing PRV sixes. They make very nice runners with a lot more torque. Lot of effort. Not for everyone.
My next PRV six will be 96X80 with four valve heads and a turbo.
JVL loves to blow his horn. Beware his engineering solutions. Measure everything/count teeth ect yourself for anything he is involved with. Every critical dimension. Every machine step. 1000 ways to get anything custom wrong. He managed one or more wrong/forgotten for everything he was involved with for me for multiple disasters in my car.