Where to position in the chassis?

[pat565]

I'm trial fitting an aluminum 5.3 into my bare chassis (71 C10), but the mounts that I'm planning to use are going to need some holes drilled either in the mounts or in the frame to get things together. I'm planning on reusing the original frame stands with the standard adapter mounts to the block.

Does anyone have a reference measurement (from engine to frame), to place these engines so that it's back towards the firewall but still look like it was meant to be there? I've heard that there are a few choices, but I would prefer to end up with the spare room at the front of the engine.

Any info would be great,
Thanks,
Pat