With this set up do I need a different length of push rod and if so what length, also will the 1.7 rollers make much of a difference or should I stick with the 1.6
CARYEMLER, I saw your PM but can't get the mobile app on my phone to let me respond.
As the other poster said, you will have to measure your PR length. Due variances in how much milling your head and block have had done, we cannot tell you what you need.
After your PR length is set and you have your pushrods, you will still need to check piston to valve clearance. I recommend doing this on every valve.
When I had 1.7s on my combo, I had plenty of clearance on cyl 5 (the one I checked PV clearance on) but didn't have enough on cyl 4 (the one that bent the exhaust valve at 5500 rpm).
I have an e303, gt40's and cobra 1.7's. I bought a stock set ford racing pushrods, I didn't measure. I lucked out. MEASURE 4 times then take a beer break, sober up and measure again.