It's no really big deal to mount a 1958-1962 hydraulic drum brake in a rigid frame. But if you place the stock baseplate 5/8”-18 threaded lug bolt in the frame casting where the up to 1957 lug goes you'll have 1/4” of unwanted space and the brake line fitting will be placed right away to the very rear. No pretty thing either.

Exchanging the 5/8” lug bolt for a Junior's offset lug with 7/8” threadless stud will eliminate the unwanted play and place the brake line banjo in the much more convenient 2 o'clock position. With its two 5/16”-24 threads the Junior's lug mounts to the same bolts as the T-shaped lug bolt.