I'm beginning to put together my performance minded 331 Caddy now. There has been a lot of discussion about interchanges between the 331, 365 and early 390. I don't know everything about this, but I have participated in some of the technical discussions and learned a lot here on the HAMB. Thanks guys! My goal is to extract some power, yet have a stock appearing 331. I don't know how much this will cost, but it probably won't be too much more than a nice 383 Chevy build. We'll see! I have no particular power goal other than as much as I can get without getting ridiculous. This means primarily off the shelf parts or modifications thereof. The work is being done at a local engine shop to my specifications. If it turns out as good as I think it will, I'm sure they will be willing to do more (once we get the recipe down). This oddball stuff is a PITA for them (my opinion- they never said so!), so I expect it to take a while. I don't want this to take priority over their normal business, and there is a lot of craftsmanship going into this which takes time. We've already waited about 6 weeks for the rods because even though they are off-the-shelf items that everyone advertises, nobody had stock. Here is the basic plan: Modified 390 crank Looooooong H-Beam rods Forged pistons, 10-11:1 range (premium unleaded pump gas) Ported early 390 heads with seat inserts Vintage aluminum flywheel (it is going into a 2600# car) The 331 will feed into a '37 LaSalle top shift trans It should yield about 398 CID when it is done. Induction will be 4 side draft single throat carbs (which I expect will choke it), but I may eventually go to 4 Weber dual throat side draft carbs. Is this of interest to anyone here?