318 head porting for the average joe

I am building a set of 675's myself now. I bought them off craigslist, and they were part of someones unfinished project. The interesting thing about them is that they have 2.02/1.60 stainless valves and lunati springs and retainers.

I've started the porting and feel pretty good about it, taking the flashing and lumps out of the ports, and smoothing around the valve guides. I have not done any cleaning up in the combustion chambers, and I'm trying to figure out how important that is, and there is also the issue of my fairly high lift cam. It looks like I need to grind down my guide boss's to accommodate the higher lift and the taller retainers. I called a shop and they wanted $100, but I'm thinking that I could possible grind these down myself with a simple grinder. Am I crazy to try this? I've looked at buying the boss cutting tools and I can't really figure out which one will work for me (I don't need to narrow them or anything, just cut them down). Any input on this? The cam is a lunati 60403 grind (.514 lift on exhaust side) stock rockers.