A Taurus more reliable than a Town Car? I guess there's a first time for everything.
I've had a couple of 80s Grand Marquis and Town Cars, and they were extremely reliable. One 80s Taurus - utter disaster. Terrible transmission, far more problems than the Panther platform cars. That said, I'd rather have a General Motors car any day.
The problem with the original reviewers car is the 4.1. We had one of these once with the 307 - plenty of torque, very reliable and durable. The question is, if you buy one with the 4.1, can you easily swap in a 307?
Forget about the 307 and put in a fuel injected Corvette 350. If price is a concern, a TBI 350cid V8 will give you plenty of power boost cheap. Add a 345 or 373 rear end and you are good to go.
Keep it all Cadillac, put one of the last true big block Cadillac engines under the hood (425 CID or 368 CID V8s); plenty of power and reliability.
Guys, there's nothing wrong with the 307, it's reliable, durable, cheap. I had many in Oldsmobiles - Delta 88s and 98s, and one in a Cadillac. The thing about the 307 was that the ones in '85 and after were a bit weak, but '84 and before were pretty good, power wise. Something about the heads.
And as far as making the gears lower - good lord, wouldn't that defeat the whole purpose of driving a Cadillac: quiet, smoothness, and relaxed high speed highway cruising? I never thought of a Cadillac as focused on acceleration.
An Olds 307 conversion is straightforward. Adding anything larger would require you to do some modifications to the engine compartment to make room for the larger engine. Not to mention that most of the auxiliary components and transmission are a straight carryover from the 4.1 to the 307.
Well you know they say that all Oldsmobile V8s are the same size in terms of external dimensions.
If you want to convert to Olds power, I'd say go with a 350 or 403. They are the same block as a 260 and 307, and offer plenty more power and torque. A stock Olds 350 puts out around 170hp and 275 lbs torque. The 403 puts out around 180hp and 320 lbs torque. They will fit in without extensive modification.
Watch out for the later Olds engines (1977-1979), as the blocks are weaker, the heads are suckier, and the overall engine designs are just less impressive than the earlier models. Watch out for the siamesed cylinder walls in the 403 if that's what you get, as the coolant sometimes can't flow between the cylinders, causing overheating.