Just completed a similar conversion to front disc, rear drums on a 51. The mounting kits available work very well, but the offset of the MC does make it difficult to fill. A couple of tricks that enable you to fill from the original hole, without crawling underneath the vehicle, can make it easier.
When filling the reservoir, I found that using a 60ml catheter tipped syringe with a short section of clear tubing allows you to add just the right amount of fluid without spilling any extra all over the floor with a funnel.
When it comes time to pull over the bail on the top, incorporate a small piece of chain (with a pull on the end) to the bail. You avoid scraping up your hand this way.
The only trouble I had was bending the tubing when it comes out of the MC. I put in a saginaw 4sp with Patrick's Hurst shifter setup. There is very little room between the shifter gates and the side of the MC - less than 1 inch.
