hi corvetter,the lt1s of the day were only produced in 3 model years 70/71/72 and are quite rare,the last of the small block screamers,they were noted for this as they were the last of the solid camshafts from the factory,the 70s are rated at 370 hp,the 71s 330 hp and 72 at 290 hp,standard specs are 4 bolt mians steel crank pink x lt1 conrods,trw pistons,70s had 11 to 1,fuiley heads,alloy high rise manifold holley double pumper rated at 780 cfm,transistorised ignition,all lt1s came with the muncie 4 speed,in a way it would be like compareing a guy that has a gtr torana and he has stuck a set of triples on the motor and some engine work and saying it has more power than a xu1,at the end of the day if the car is what you want and the price is right than go for it.as far as a big block gos they came with them fitted from the factory so putting one is not a problem,be warned though lots of money,if you want a big block my adv\ise is buy one that has allready got one,hope this helps.