Machine shop. Shouldn't cost too much if you can find someone to do it. I had a buddy that use an angle grinder but that's pretty sketchy
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You could just run a stock cam and not have to worry about it. Gnarls on here ran some pulls on a bunch of cam profiles on some kind of desktop dyno and the stock cam profile isn't exactly bad unless you are going with a really nasty cam. The stock cam makes more bottom end, has a really broad torque sweet spot and wraps out pretty well too. I am running it in a 20r/22r hybrid and after some tuning with an adjustable cam gear and getting the carb freed up and dialed in I am fairly impressed with the whole setup over a stock 22r. It's not a 3RZ but it's getting there. I can tell you if this engine was in a smaller, lighter pickup or a car it would absolutely rip!
Here this thread has a whole bunch of spreadsheets in it that Gnarly posted up. I think some of the later ones even had the 20r data in the hypotheticals:
http://board.marlincrawler.com/index.php?topic=100575.0
