The biggest issues with on frame, Is be sure and have a good size access hole in the floor to fill and service the M/C, also getting the air out of the system, having a frame mount may put the M/C lower than the calipers you will need residual valves inline to the brakes at least 2, 1 front one rear, you may need 4 , 1 per wheel.

It is a cleaner look, and I like it, But I choose to install swing pedals and a firewall mount, no its not as clean a look, but it is easy to service and no residual valves required.

Godspeed
MrC.