as already mentioned,the Camaro/Nova could be cheaper,but the rad. and sheet metal and bumper mount can be a problem.Mine has a Nova.It works fine,but is a bit too wide,so with two people in it tires can rub on the fenders in tight turns.
The M11 kit is designed for your frame.Clearances and engineering have already been dealt with for you.
If money is the main issue,buy the frame you mentioned for $1000.
I sure used the word "mentioned" a lot,,sorry
Boyd

1952 Chevy 1/2-Ton