A type 1 hipo engine can be built for the least cost. You can get 120hp+ for a carb engine, if you are going the PEFI route, with proper headwork, you can get 160hp on pump gas easy. Remember this is only a 250lbs. engine with the shroud, fan, alt., etc. Done right with the PEFI system $5500- $8000 depending on size, parts, etc. This is more than enough to smoke the tires on a lightweight car. Don’t know about the trans fitting.
A type 4 with PEFI will cost about 20% more and will give you about 10-20% more power. If you use nickies you may hit the 200hp mark (big maybe) but add $3000 extra to the price. The T4 has a flat torque curve if built right.
I don’t know enough about the 6 to tell you what it is worth/hp, the other guys can help you with that. The six will give you higher hp out of a stock engine, so it should last longer than the fours. All the six guys will brag that it sounds better, for what ever that’s worth.