I want to put a Hemi into my '70 factory 383 Barracuda, were the Hemi cars any different in the engine bay & what mods might I have to do to make it actually fit?

It's a mega block with early Mopar dual plug heads & pressed alloy covers, Cheers

there isn't any difference under the hood on E bodies.
you might have problems with the right valve cover hitting the shock tower, under hard acceleration, if you use taller cast covers.
also don't use 2 1/4" tube headers if you want to run power steering, hits the box.

Cheers for that Mr T2U

I don't think I'll be doing too much hard acceleration and the covers I have at the moment are quite low just like the factory single plug ones.

My car does not have power steering, but I'll probably go with 2 1/8" rather than 2 1/4" headers.

What engine mounts do you use? Will it Clear power Brakes?

Block hasn't arrived yet, some have 440 while some have Hemi mounts, I'll have to wait & see, then I'll buy mounts to suit.

I'll probably get a smaller diameter booster, maybe off an Aussie Mopar.

I installed a repop hemi K frame w/ Shumacher Poly Lock mounts when putting the hemi in my 383 RT Challenger. Don't know if the inside dimensions of the bay are wider than the Cuda, but my stock hemi valve covers cleared just fine. Only problem was with the stock power steering box being only 1/16" away from the TTI headers. I had Firm Feel make
a J body stage 2 box & it clears fine.

The engine compartment is the same, but the crossmember the engine sits on is NOT. You will need a Hemi K member or some type of conversion engine mount, the problem w the conversion mounts is finding headers to work with them.