brake bias question?

[bianchi1]

i am now thinking about putting those mazda 4 piston calipers on the rear of my spider, keeping the soild rears thu( fronts are vented)but in your thoughts, are the rear brakes more prone to lock up before the fronts?if so ,i am thinking about useing a bias adjuster to correct for this. i look at porshe cars for the master cly. but there cars are bolted on at a 45 # angle so that wont work ,and looked at ferrari master cly. also, not there also..i am thinking about calling/ e-mailing ate. , and asking about witch master cly. might have the bias i might need.