Thinking of having 0.100" milled off of a spare, clean, high head I have. I'm also thinking while pulling the head I should add new valves from Lang's (standard 312 size). I'd really like to put a new cam in the motor at some point. Keep going back and forth from Stipes 250 or Stipes 280. I've also considered having a factory cam reground to improve performance but don't know who I'd go to for that. I want a little improvement in my high end but don't want to really sacrifice my low end torque too much. My question is: if I go with a cam that has higher lift on a milled down head, am I running the risk of valve and head contact here?

Your last question, head valve clearance; NO problem at all!!!
However you would gain a LOT more with a replacement head( the Prus works very well)
Chaffin sells a reground cam that people seem to like

Thanks for the response. I'm keeping these things in mind for 2 different cars. One is my 26 Coupe, which I plan to add a Prus head to. Sounds like a reground cam or a 280 cam will clear with a Prus head then and the increased lift, right? The milling I'm considering for my grandfather's 23 Runabout. He's already told me he intends for me to inherit it when he's gone. I'd like to do some modification to it and run the Montana 500 with it, something he has always wanted to try.

"I'd like to do some modification to it and run the Montana 500 with it..."

But Matt, Montana 500 cars are stock, not modified. (wink, wink)

Check out Jeremy's thread, he had good luck with a reground cam.

http://www.mtfca.com/discus/messages/708324/767462.html?1498588871