need advice on my 454 heads-positive seals, spring install..

[Silent viewer]

i am currently building a gen vi 454 for a 27' baja performance boat. i upgraded to a higher lift cam and it made it so i that i had to upgrade my springs. i bought a set of isky springs, comp cams retainers and locks, conversion studs and roller rockers. i rented the tool to swap out the springs and took one out and figured out that the stock valve stem seals and rotators where not gonna work, keep in mind i am new to head work. so now i am taking the heads to the machine shop to get machined for positive seals and i am deabating whether or not i want to put the heads back together myself or pay the shop? i am not doing a valve job because the heads only have 50 hours or them and look like new so if i were to put them together myself do i need to be concerened with measuring all of the parts and use shims if needed or since these have never had work done on them and have minumal usage can i just throw it all back together with each valve in its original location? i am on a tight budget so i would like to be able to do it myself but dont want to eff something up. another question, if you dont measure and shim what is the worst thing that can happen? thanks in advance 😀

 

[bigblockmadness]

if you were to not measure the install height you might not get the propper spring pressures for your cam. yu should be able to install them your self.
not enough shims = low seat pressures, to many shims = high seat pressures. If you took them apart and remember where all the shims went then you shold be ok.