Welcome to the site. For a completed 70-71 E body, with the 440-6, or HEMI, even clones, are gonna be alot of $$$. Especially for 4 speeds.
I got to agree here - this isn't going to be one of those "budget" cars - good taste though!
I've seen "clone" Hemi cars ripping through several tens of thousands already.
Glad I got my big block 4 speed before the boom realy hit - haha, now that I think of it the guy sold me my car to do the resto on a 72 Vette - sucker.
A good thought would be maybe to lean towards the, and I use it for lack of a better idea, less desireable 72-74 and drop your own big block into it.
Even though I say less desireable, I'm only saying what the current "demand" seems to be for 70-71 and I love my 73.