Okay guys, looks like the 300 rebuild plan is a go. As mentioned before, I acquired an aluminum 4bbl intake, but haven't had any luck finding the right Rochester 4GC carb. Any thoughts on a suitable replacement? What new carb has the correct mounting flange and bore size so the butterflies clear the bores of the intake? I'm thinking around 500CFM?
I measured the fan clutch to block face on my 68 Rivi and came up with 9 inches. That puts it in the radiator on the LeSabre. And that's with oly about 4-5 inches at the firewall to rear of block. Not only that the bellhousing sits high enough as shown in pics from under car I sent that I'm almost certain that you will have to do major surgery to the firewall.
You are probably right to choose repairing the 300 for a time efficient solution. Did you see the Hot Rod magazine article(March 2011) about building the 300? Unfortunately failed to mention cost of machine work.
For me The complications definitely mean next fall before I can work on the LeSabre.