340/360 Heads on a 318

I had a 318 years ago I put in my Dart after I blew up my 340 it was a 70 318 with 60,000 miles and a mild cam it went 13.80s I put on a set of 1.88 valve fairly stock 360 heads and was going 13.20s with 3.91 gears and 1 5/8 headers it had a 904 with a 10 inch convertor. I put in an 8 inch convertor and went a best of 12.67. Every combo is different.