Availability and "Bang for the Buck" are factors to consider when choosing a powertrain...

While people fight with machetes for premium models, a lot of people build really cool cars from base models. And often they swap engines and transmissions. Here's some guidelines on which ones are easy to do and offer a big performance gain for minimal dollar outlay. # 1. Lets say you have a 1964-67 Chevelle, LeMans,or Olds Cutlass, or Buick Skylark. GM had a rule that no intermediate could have a standard engine over 330 cubic inches. ( The 389 Pontiacs, 396 Chevys and 400 Olds and Buicks were options. Semantics,but thats GM back then. ) If you have a LeMans with the 326 / ST300 powertrain the way to go would be get a 400 and a TH350. The reason is Pontiac engines are externally identical from a 326 to a 455, so it's literally a bolt-in swap. 400's were used in almost every model from '67-78, and make a ton more power than a 326. A 326 ( or a 350 for that matter ) isn't worth hopping up because the big-port,big valve heads needed to make serious power can't be used because of their small bore design. The valves will hit the block. People talk about notching the block for clearance, but why? For what you'd spend on machine work,you could easily buy a 400 or 455 that will still make way more power for less money than a hopped up 326 or 350!!  As for the tranny-I've said before a 3-speed TH350 is the exact same size and uses the same rear trans mount and driveshaft yoke as the Powerglide / ST300. It's also a bolt-in swap and will give a huge performance increase over the 2-speed autos. Now if you have an Olds Cutlass or Buick Skylark it's slightly different. For the Cutlass the way to go would be a 403. They are externally identical to a 330 or 350, but have 53-73 more cubes! Although they were only used from '76-79, their are millions of them around as they were used in almost every GM model outside of Chevys. With the Buick you should chuck the 300 or 327 V8 and get a '68-77 350. The reason is there are zero replacement parts out there for the 300 / 327 and the 350s, while being much easier to get parts for, also make way more power and torque than the obsolete ones. Now if you have a Chevelle or El Camino, there's two ways to go. If the car has a 283, I'd pull it and save it in case you ever want to sell the car to someone who wants it totally original, and just drop in a 350 or a 383 stroker. A 350 or 383 would cost no more to build than a 283, but would easily make way more power and torque. That's the beauty of a small-block Chevy-major hp for very low bucks. If the car has a 327, the shoe is on the other foot. A 327 is a great performance engine, and changing to a 350 would be a waste a time. Stock or modified, a 350 will only make about 20hp more than 327. That's not worth messing with. And swapping the "Powerslide" for a TH350 is the just what the Dr ordered here as well. These guidelines can be applied to other makes as well. If you've got an AMC Javelin ( or a Hornet or Gremlin-their short wheelbase and light weight makes them great drag racers ) with a 304, a 360 is a bolt-in swap. And since they were used in Jeep Grand Wagoneers until 1993, they are plentiful in junkyards. If you've got a Mopar with a 318-a 360 Magnum would be the way to go. They were used in millions of Dodge trucks and vans and Jeep Cherokees, so their plentiful in jumkyards. And the "Magnum" heads breathe better than any other factory head and many aftermarket ones. And Edelbrock makes intakes to run a 4bbl carb on them. If you've got an early Mustang or Fairlane or Falcon / Comet with a 260 or 289, I'd get a later model 302 and build that. And with a small-block Ford,you could build a 347 easily and cheaply that would make way more power and torque than a 289. All of these swaps offer huge improvements in performance for very low bucks and and hassle-free installations! Something to think about. Mastermind