Reeder for sure. Since we're not allowed to post links to help folks out when looking for stuff, do a google search on "Reeder Grinder Chassis" and the first hit should be the one to take you direct to the Reeder page for the grinder chassis. Or, to the main page, click the "Shop" at top, then scroll down till you find the grinder chassis for $795. While the $200 set of wheels by Reeder are the best, for $100 you can get a very decent set that will do the job just fine by doing a search on ebay for item #284887453901.
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Next you'll need a motor and VFD This Chinese VFD will work just fine and last for several years even though it's a NEMA 1 enclosure. Just put a filter over the air inlets to prevent metal dust from getting inside. Item #B0B1WDHNB9 on Amazon. This 1.5 hp, 3 ph motor will do a "decent" job, but a 2hp would be just right. I'd go with a 3450 rpm motor, when used with a 5" drive wheel it gives 5,000 SFPM belt speed. Item #B073F5B3Z3 will lead you to the 1.5 hp motor on Amazon. I would normally go with an IronHorse 3 ph motor but those things have gotten expensive - and "Out of Stock". You might do a search on ebay for item # 125405351044 which is a 2hp, 3ph motor to see what the bidding price will be.
Good luck and have fun - the above provides a variable speed Reeder grinder complete ready to grind. Any grinder you get NEEDS to be variable speed.