I've got need of some tech help, I dropped a set of 915 big block heads off at my buddies machine shop, having bigger valves, hardened seats guides & cut them .030 off the deck & .037 off the intake.. Anyway I got a call today & he's concerned about opening the exhaust up enough to put a seat in... Currently the exhaust valve is 1.60 & I bought 1.81 valves, he said he's comfortable with opening enough to run that size valve with out the seat but to put in a seat he's concerned about hitting water.... I thought this was a common upgrade? Thoughts? Thank you for your time & expertise...