Putting together a list of items to buy for a front disc conversion on my 5 Lug ,drum brake '73 Comet (mostly stock). From my research on here, many use the 14377 front disc kit along with the Wilwood Proportioning Valve (260-8419). What I can't seem to figure out is which master cylinder is required. I see that Wilwood list different bore sizes and me not having much background with these things, am looking for clarification from the group of what to go with. Thank you.