Tapper to roller cam conversion
If your motor is apart, I would highly recommend you first and foremost get the lifter bores bushed. If you're goin' roller, now is NOT the time to save money. I can almost guarantee you'll have oiling issues just dropping those pricey roller lifters into the factory lifter bores. Even if you don't, being bushed, it will live a long happy life. Trust me.
Next you need a quality set of lifters. BAM, Comp, Crane.......there's plenty of choices. None are cheap.
All you need now is a good bronze gear intermediate shaft and your cam. Easy peasy.
Last thing I'll say is consider a SOLID roller instead. I don't know why they even make hydraulic roller lifters. Checking your valves once a year is a simple 1/2 hour job. If you really take your time.