351CID flat to roller cam

I have a 1985 351CID windsor smallblock that i am rebuilding, and i was wondering if it is possible to replace the stock hydraulic flat tappet valvetrain with a hydraulic roller type valvetrain. does anyone make a kit for this? is there any machining involved?

Comp provides an excellent "retro-fit" kit for the small Fords. Highly recommend Xtreme Energy Series. Modern cam design, Comp quality. Get the "K" kit. It comes with springs, retainers, locks, cam, lifters, and even the timing set recommended for that cam. Rollers are NOT "cheap". Expect to pay between $850 and $1K for the complete package. Is it worth it? Only you can answer that. You WILL get performance and drivability gains.