Vintage race engine (273 vs. Slant 6)
Back when I worked at a dodge dealership we had a chrysler 300 come in that road race in Mexico I believe it was that series this was about 13 years ago.
When I mentioned the LD4B I was thinking of a carb adapter. ( I run a 500cfm Holley 4412 on my oval track Mopar) plus it would help with the front weight and they were avalible early in the 60's for the 273. The chevy's and the ford's would NOT scare me, the chrysler has a better rod ratio, better heads, rocker arms ect.
Closed chamber head with some quinch to run there junk fuel..... this sounds like fun when do we start!