Ok pontic head gurus here's my issue. I have a pair of '69 heads with a casting number of "62" These should be for a '69 400/428 4bbl. I need an exhaust, but all I've been able to find are to short. The original valve are 5.080" over all length, but the replacemets I've found are only 4.972" overall length. Everything else is correct 1.77 valve with a stem diameter of .340 The shorter length is my concern or is it just my retentive side coming out

Thanks