After having owned a 63 Pontiac Laurentian (a Canadian Chevy in Pontiac clothing), that had been equipped with a BBC with a solid engine mount on the LH side by the previous owner, I can tell you, those X frame chassis are pretty darned easy to permanently twist up. My old 63 would sit square at the rear then I could sight down the body side to see the twist in the front.

That RS chassis is a work of art, and something much neded for an X frame car.

I've made the decision to go with a Schwartz performance frame:D