I need to mock up a LS2/5 speed in a 1970 chevelle. I plan on fabricating frame reinforcements that also tie in as a tranny mount, thus the main reason for full mock-up. If I purchased the motor when im ready to fit it to the frame, the 2 year warranty will most likely expire by the time I get the car running. Anyone have any bright ideas to do a mock up without the LS2? I've been told that the LS series motors sit a tad bit lower that a standard s/b 350, making it very difficult to perform an acurrate fitting...

Is it the same as an LS1 block?

http://www.vanpeltsales.com/FH_web/replica-chev-sbprices.htm

Is it the same as an LS1 block?

Yep! And there are companies out there that make this swap easy. They have adapter plates for your small-block mounts, headers, and crossmembers.

Or, http://store.summitracing.com/partdetail.asp?part=PYP%2D2046&autoview=sku

So the LS1 shares the same dimensions as a 350? Im mostly concerned about the headers and how high or low they will be... I'll be making a custom tranny crossmember so I want the exhaust to pass underneath the crossmember...

Don't quite know what you mean by "shares the same dimensions as a 350" but there is NOTHING even similar between the two. The only thing even close is the bore spacing and bellhousing patten and its not actually the same. Header port spacing and the face angle of the ports are completely different. I have a '33 with a ZZ-4 and a C6 with a LS-2 and believe me, nothing is the same.

Thanks for the feedback!!!

i am in the procesess of putting a LS2 and a 6sp from a gto into a 67 mustang convertible. should be fun to make a ford run fast.

built ford tough with chevy stuff!!^^

call around to junkyards and ask if they have any blowed up 4.8 or 5.3's out of a 99 and newer truck- you should be able to get a junk motor for a couple hundred $$$.
they might not be 100% the same, but as far as i know, every Gen 3 engine shares the same header flange and port locations, and the engine is externally identical once you take the accessories and balancer off.
if you were closer, i'd let you borrow the 98 Camaro LS1 i've got in the barn that has a hole in each side where a connecting rods flung around after snapping in two.