What material are/will the valve seats be made of? The Sykes Pickavant set I still have somewhere is OK on cast iron, but won't touch the seat inserts that modern production motors use. The carbide seat cutters are supposed to be good for the hard seats, but even the Indian made ones aren't cheap.
You could use a single point pilot cutter tool providing that you can secure the block/head casting to the table with the valve guide true to the cutter pilot. I made this one with a carbide toolbit to reshape the cast in 'valve guides' on a vintage motor. It wouldn't be difficult to produce a single point cutter with the correct 30 or 45 degree angle to do the valve seat in the same way.

I do quite a bit of work on old cars, so bought a Black & Decker 'Vibro Centric' seat grinding kit along with the valve grinder. Once the stones are dressed with a Diamond, they produce excellent results. I've seen the Vibro Centric kits sell for not much money at boot fairs, they seem to be a bit spendy when they turn up on ebay though.