I don't know how much help this will be, as most of you guys doing new builds already have your donor blocks... but...

I found 2 a little harder to find magnum race blocks, 2 "r3" blocks. I don't know if any of you follow any of the crazy builds over on some of the r/t forums... but apparently these are a little hard to come by, and are usually pretty expensive.

first one looks like an unused 48 degree block w. 4.125" bore. It says it can goto 4.22" by my estimation, stock 4" stroke would put you at about 427ci and 4.22" bore would put you about 448". that's quite a bit.

http://chucker54.stores.yahoo.net/mor3bl4bo.html

apparently what's nice about the blocks is that they have a higher deck, and are just better castings than stock magnums... and can really handle the power.

the second is a used 58 degree block.

http://chucker54.stores.yahoo.net/r3bareblock2.html

not sure if anybody has any interest... but i was wondering if the angle measure affects the type of heads/intake that can be used? it says tappet angle but i'm not quite sure what that describes.

 

Those blocks would be bad a$$! Personally, for my build though, I can't afford a block like that... I bought the entire complete engine for $250, and I'm looking to spend less than $2000 on the entire build, but like all my other projects I'm sure I'll end up way over budget. A 427 sure would be a lot sicker than a 408 though!

The tappet (as far as I know, so correct me if I'm wrong) is another name for the lifters. I think "tappet angle" means the angle the lifters are sticking out of the top of the block. It sounds in the description like you can't use hydraulic roller lifters.

 

Nice, thats about the same price the dealers sells the new 340 blocks for. The lifter (tappet) angle was changed to make the lifter and push rod parallel .