AC engined cars tend to be a bit less valuable than Bristol engined cars secondary to difference in performance. Rebuilding a Bristol might cost you up to $20K, I've rebuilt my AC engine. Lots, if not all parts are now available again through Robin Woolmer and Rod Briggs. Or an entire fresh built AC motor can be done... I like my AC motor. It runs very well, so far proven reliable and does about 25 miles to the gallon.... I would venture to say, without checking all of my receipts, that the complete rebuild of my engine set me back about $8K, but don't hold me to that. I would guess the engine to have about 100HP at this time. I used new Con Rods, cam, valves, springs, pistons, sleeves, distributor (123 ignition)etc, etc. If I remember right the timing gearing and chain were in great shape. We re-ground the Crank and fit new bearings. If you're in the Michigan region, I can put you in touch with my engine builder, in case you decide on an AC engine.