http://www.mustangmonthly.com/howto/17279/index.html


and do the stock wheels fit back on like they say?  

Not that this answers your question, but I have a 65, 200 automatic coupe.  I've just purchased the kit from www.discbrakeswap.com with the power brake unit, and lemme tell ya, this is a kickass kit.  Now, I have a 7.25 (or whatever, not an 8") rearend.  What I plan to do there is get the axles redrilled for 5 lug, get the stock 9" drums redrilled for 5 lug, and I should be in business.  I'm telling you this, cause I thought I'd be stuck doing the 4 lug conversion cause I didn't want to change the rearend at this time.  This solves the issue, but I got to get new wheels...  Hope this helps somewhat!  

BTW: it's the Stainless Steel Brakes' Six-Cylinder Disc Brake Conversion PN A120-5
http://www.stainlesssteelbrakes.com/products/detail/442/?make=Ford&model=Mustang&year=1965