What allot of folks forget,, is the fact that some small block Chevy's run like wild cats,, and others are dogs.. What you started off with, and ended up with is allot of work, and some luck for it performance. My 6/1 is mounted on a wheel cart like your and runs well,, but my 14/1 is lag screwed down to 8" thick 6'x6' slab of concrete. It float the whole pad,, and is always rockin..
Thanks for the time investment, and the time spent with passing it along.
sodbust