Since you won't have much time, you may wanna consider buying a crate engine.

Len Williams can build you a 455 with 6x heads for about $5000. And he furnishes the block. So, if you buy from him, you can sell your engine, and get your money back. Len is considered a competent Pontiac engine builder. And I haven't found any better prices, for equal quality build.

http://lenwilliamsautomachine.com/455_Long_Block.html

Here's his basic 400 block stroker shortblock, for $3500.

http://lenwilliamsautomachine.com/455_Short_Block.html

There are all sorts of options. He can build it with alum heads, forged crank, different cams, or most anything you want.

http://lenwilliamsautomachine.com/400_Edelbrock_Heads.html

If you go with a stroker, & alum heads, you'll need the larger chamber heads, to keep the compression down.

The biggest KRE chambers are 85cc. These will give you about 10.5:1 CR, or a hair less, with flat top pistons. 10.5 is said to be safe with pump gas, when using alum heads.

http://www.krepower.com/Pontiac%20Aluminum%20D-port%20Cylinder%20Heads.htm

The E-heads have 87cc chambers.

http://butlerperformance.com/i-24452926-...-dport-290.html

Here's a compression calculator.

http://www.wallaceracing.com/cr_test2.php