We used the 1970 starter system connected directly to the battery and mounted on the left side of the block, not the computer starter system. The wire harness is set up for the starter to be on the right side of the engine, so you will need to un-tape the harness and re-direct the wiring to...
Not to promote another forum but I did a whole write up on my 392 swap in my '70 Cuda, including part numbers and steps. https://forum.e-bodies.org/modern-hemi-swaps/26/392-hemi-swap-2016/67/
TTI fit perfect, Doug's are questionable. 3" is overkill unless you have (or are planning) a high horsepower/tq 440, more like a stroker. Plenty of videos our there comparing mufflers, its a personal liking.
Selling my 340 with 6 barrel set up. Included is a correct steel air cleaner, 1970 block, manifolds, O heads, 6 barrel Holley carbs/linkage and Edelbrock intake manifold, alternator, distributor, pulleys, power steering pump. This is a drop in and go complete set up.
$3800