I have a 1970 convertible with a rusted out frame and a cracked engine cradle. I found a frame from a 1970 California skylark coupe. I can box the frame with a strengthening kit. Will that kit make the coupe frame strong enough for the convertible? I’m also thinking of putting a LS in it. This car was purchased by my mother in 1970 so it’s all original with matching engine and tranny. Should I clean up and rebuild the old 350 and put it back in.