Im fixing up my 74 and im almost done with the front suspension, just gotta order some parts. Since im ordering parts im thinkin i might as well order the proportion valve and set up, only problem is i dont know what to go with? om not sure wether to go with either a firewall mounted or a frame mounted one. im ordering from classicperform and dont know what to go with. my stock one that i got rid of look like its a frame mounted set up according to classicperform. im also wondering under what applications would you use an adjustable proportion valve.

heres what im looking at just find proportion valves down the page

1962-67 Chevy II / Nova Parts. The Finest in Suspension, Brakes, Steering and Accessories.

thanks to anyone who can offer advice