Brake line question

[k51977blazer]

I have a 79 k5 blazer my line broke it's the line from the pro portioning valve to the rear brake line. My question is the guy who had it before me has a 3/16 inch line going from the proportioning valve to about the middle of my truck then goes into a union then goes into a 1/4 line , the guy at the auto parts store tells me I should run 1/4 line all the way back and just put a adapter from the line to the proporting valve, what are your guys thoughts

 

[diesel4me]

Original line was 1/4" all the way from the prop. valve to the rear brake hose..

I noticed newer trucks have 3/16" line all the way to the rear,so I dont know how much difference it really makes..I just put back what was there to begin with!..