68 barracuda steering pump question

Found the rebuild kit and it had everything needed in there.
followed the threads on rebuilding and seems to have the same problem as before with p/s fluid making its way out the cap during driving.
I decided to ignore the dipstick on the p/s cap and reduced the level of the p/s fluid in the reservoir to the bottom of the filler neck. This seems to have done the trick- no more overflowing out from under the filler cap while driving so far.
What I am thinking is that the p/s filler cap is not the correct one and therefore it has a dipstick that is a different length than what I should have on the pump to get an accurate full read.
Does anyone know what the correct TRW p/s cap is? (and if there is only one?) and what the dipstick length is on it? (or if it has a dipstick at all?)