JB, let me see if I have this all straight:
The significant (noticeable) fish populations in the pond are GShiners and CC. There may be a Blue Cat, an LMB, and perhaps residual HBG and/or their descendants. Also possible are left over bullheads and assorted sunfish, but you're not seeing them.
This amateur will now take a look at the rest of your questions and submit my opinions for extensive rebuttal and correction by more experienced minds.
I do not feed them but want to start.
I am sure many of your existing CC and GShiners will quickly start eating feed if supplied. If I remember correctly, 6 year old CC should have years of life span left and will put on weight and size. GShiners will put on size and probably spawn better with added food. Feeding may also reveal fish (Blue Cat, sunfish, Bullheads(?)) you may/may not have (probably not the LMB, though).
Do I need to worry about the large number of golden shiners in my pond
Depends on what you want for the pond. I doubt your CC will ever eliminate the Shiners; they will utilize them for food. If the BC/LMB are alive & well they'll put some away, too. But I doubt you have enough predator aggressiveness now to dent Shiner numbers. If you add more predators, probably any kind you stock would make use of the GShiners as forage.
The perch/HBG population is probably down but not out, so should I worry about them?
After 6 years, the original HGB you stocked are probably all gone. My guess is that if you are not noticing any sunfish, whatever offspring the HGB or native sunfish have left in the pond are in such small numbers that, if you decide to stock a new predator (LMB, HSB, even more Cats), the sunfish remnants will remain under control. Also, if you stock regular BG for forage, small numbers of miscellaneous sunfish shouldn't mess up your gene pool if predators are around to eat any slender Green Sunfish or genetically inferior HBG descendants.
Considering my info, anyone wanna guess what the biggest crop of fish may weigh
I won't guess how much, but I would put my money on the Shiners as making up the biggest chunk of your biomass by a wide margin.
If I were you, I think I'd start feeding, fish more, and see what I more could learn about the fish in the pond. You have the potential of having enough problems (Bullheads, HBG offspring, Green Sunfish) to at least consider renovating if any of them show up in numbers sufficient to present a problem with your plans for the pond.