The more expensive option but if you like to ride fast and stop fast

This mild steel

For use with DOT 3 or DOT 4 brake fluid

These threaded steel bungs are 3/4" diameter and are drilled and tapped all the way through with 1/4"-20 thread

you also need a set of six fiber plates to complete your clutch now that you burned it up doing tough-guy burnouts

#8618-20 Big Bore Headbolt & Washer Kit 1949-Up Harley-Davidson Panhead/Shovelhead - Black Tire Size_21" The more expensive option butHi strength, chrome moly 12 point bolts utilize 7 16 box wrench for ample clearance on big bore cylinders. Fits 1948 Up Panhead and Shovelhead models. Made in Ohio, USA.