[Pvmt-Pndr]

You've done the cheap things aside from trying to bump the timing to see if there is room for improvement, I assume your spark plugs are gaped to .045 and not the .030 for points. Even if there is it's not going to be substantial. My truck is 8500 with a 427 that I just went through and empty on a flat road I'm not impressed (I maybe expecting too much, I also haven't pulled a load with it yet) in comparison to today's gas engine and compared to a diesel option there's 0 comparison. (My opinion).

What I have read a lot of is that a 427 will out pull the 366 in the hills/mountains any day of the week. It becomes more apparent when you do the same mods to did to the 366 to the 427.

Since you have a 4 speed I wonder if a 5 speed or even more gears than that would be helpful to keep that 366 in its peak rpm range. $4,700 seems like a large amount to put into something without guaranteed results.