1964 F-85 Cutlass engine

I am working on a '64 Cutlass which has a 330,4 bbl carb,high compression engine in it. It has MORE THAN 1 Hyd valve lifter with issues (leak down--- etc). I plan on replacing ALL 16 lifters--and was wondering if it would be a good time to also replace ALL the PUSHRODS TOO. I have not ,as yet , opened it up to see what I have--but would like some opinions on whether or not the PUSHRODS should be changed out also. I may find a rocker arm or two that will show wear and need replacement--and wonder if they ALL should be replaced--or just the BAD ones. in other words is it OK to run NEW with OLD and not cause a problem?

Thanks in advance for the feed-back.

Pitman

You may not have a choice to mix old an new (not that I would have a problem with it). Your 64 motor has the one-year-only shaft-mounted rocker arms. All Olds engines from 1965-1990 use rockers mounted on individual pivot trunnions. Parts availability for the 1964 motors is limited. The only way to convert to the later style rockers is to change the heads, as your #1 castings are machined for the shaft mount rockers only. When replacing lifters, soak them in a can full of motor oil before installing them to fill them and also use break-in lube on the face of the lifter to avoid damage to the cam lobes.

The problem with replacing more than just the minimum is the MIGHTASWELLS, which rapidly turn into a body-off restoration. (Well, they do for me. )