what stones would you use to port out the head?

im planning to do this on my spare motor. I have a grinder and stones but I dont want to touch it until I make sure im using the right ones. Ill probably just do the exhaust to begin with then work my way to the intake, if i can get a custom intake plenum made.

use the stones last for smoothing. get large spiral porting bits with long shaft.

Use carbide burs with the wide flutes to keepthe bur from getting clogged. I wouldn't use stones at all since they'll get clogged with aluminum pretty quickly and become useless. Once you get to your desired port shape, use a abrasive rolls, in progressively finer grits, until you get smooth transitiions and surfaces.
You will need a separate mandrel for the abrasive rolls.

Keep the intake ports rough (finish with 80 grit) and get the exhaust ports as smooth as possible.

Stones? Taking it back to the old school days.

Use carbide burs with the wide flutes to keepthe bur from getting clogged. I wouldn't use stones at all since they'll get clogged with aluminum pretty quickly and become useless. Once you get to your desired port shape, use a abrasive rolls, in progressively finer grits, until you get smooth transitiions and surfaces.
You will need a separate mandrel for the abrasive rolls.

Keep the intake ports rough (finish with 80 grit) and get the exhaust ports as smooth as possible.

thanks guys for the tips. Question, on the carbide burs and abrasive rolls, are these the correct terms or generic? Are these widely available or something i would need to order online?

thanks guys for the tips. Question, on the carbide burs and abrasive rolls, are these the correct terms or generic? Are these widely available or something i would need to order online?
Yup....those are the standard terms, BUT you'll probably want extended shank carbide burs to reach wayyyy into the ports. Standard Abrasives is the usual online place to get stuff, but if you call around to the local industrial abrasive suplly companies, you can usually get things cheaper.
When I was going through alot of abrasive, or "cartridge" rolls per week, I ordered from a local place here in Los Angeles. L&L abrasive supply (323) 264-1371. I got assortments of straight cartridge rolls (cylindrical) and tapered (almost Christmas tree lookin) in 80 to 240 grits. The tapered ones helped make the rtight angle transitions nice and smooth because of the smaller diameter near the tip, while the cylindircal cartridge rolls were good for big, flat surfaces. Goodson engine supply has a good selection of cartridge rolls and carbide burs.
http://www.goodson.com/store/template/product_display.php?NID=150&SID=21554ded99290dc5c752d39c2786497c
The extended shank carbide burrs for aluminum should be at least 6" long. You want to be able to get into the bowl area right above the valve to make the transitiions smooth and take off some material around the valve guide.
Wear your goggles and wear a particle mask. Aluminum shards in the eye are no fun.