There is another option that at the end of the day will give you a 275/290 HP engine in bone stock configuration and will be less money overall than moding the 250. Be aware that the intake ports on the 250 make it hard to get a good tune with EFI unless you run TBI. Tell your buddy they are like a mini head.

www.carcraft.com/techarticles/ccrp_1108_turbocharged_vortec_inline_six/

www.vortec4200.com

Add a turbo to the stock 4200 engine and you have a 400HP engine at 8# of boost.

2005 4200 engines are going for about $1200 complete with everything to do the swap.

Whats needed besides what you get from the wreckers is:

modified oil pan or a rear sump oil pan < ~$650
modified wire harness $500
and build a set of engine mounts


Last edited by efi-diy; 08/14/14 12:35 PM.
51 GMC 4.2 turbo
Can't solved today's problems using the same technology/thinking that created them