I dunno if I suggested this, but you could consider speaking to a head porter, telling them it's a not a million dollar budget job, maybe they'd be willing to do the work on one intake and exhaust, and let you copy them for the rest, then they'd do the valve/seat/throat cuts as a final thing. Probably save aboout 3-4 hours of labour charges (a basic pocket port probably takes around 30 minutes per port on these sort of heads for a very experienced person)