I'm putting PM Brake Calipers on my 05 Fatty, 6 Pot on front (Single Disc) & 4 Pot on rear. I was reading somewhere that the standard master cylinder port sizes are OK, (mainly for 6 Pot I think) is this true.

If not what port sizes are recommended for this setup.

Cheers in advance

The P/M site suggest using 11/16" master cylinder on their 4 and 6 pot calipers, the one used for dual disc setups,  my suppler said that it is not necessary but my setup will be Brembo 4 pot with the big Brembo disc 12.6" on the front. But your system on the front should work good due to the tyre size, don't know about the back maybe you should try a s/s braided line first to get some feel because under heavy the back will lock up even with the standard caliper, and in that situation the back is only used for steering. But I will see if my lever travel and feel is the same as is now I might change to the 11/16" M/C because my bike runs DOT 5 which is a compressible fluid.

Any way best of luck with your request for information on such a complex question, maybe if it had something to do with chrome do-dads there might be more responses

Cheers for your response stinga, I forgot to also mention that I will be run'in Goodridge Braided Stainless Brake lines, maybe that might be enough but I will wait for more responses. Hopefully Scotty may have some valuable advice