The D5 head approach is a black hole you don't want to get near. It will suck all your cash out of your wallet and you still won't have all the parts needed - special block, heads, intake, headers, rocker arms and stands, etc. Hemi Fred had a pile of this stuff and even he didn't have enough to put one together. I wanted one head for a souvenir, but he wanted to sell all of it.

Maybe you meant the D6 heads, which were aluminum, dual plug versions of the D4. The twin distributor drives are hard to get the old ones, but you might be able to adapt one from the alcohol or nitro racers (they use mags). Valve covers, MP used to sell a cast version, but one was for a BAE Fat Head and something was different where it wouldn't fit a standard Hemi head.

A coil-on-plug setup would be the cool way to go. I'd suggest sticking with the single plugs though. There are plenty of places to spend money on a Hemi. The SS/AH guys are pushing 1000 HP on single plugs.