Ciao Derek-
Wow, I certainly applaud you for trying to grow huge things in our short summers. I go to the Royal Agricultural Fair every year so I know it's possible. Personally, I've never been able to get my pumpkins or winter squashes to even reach market size. I talked to the guy with the prize-winning pumpkin at the fair last year and he said that he culls all of the forming fruit but one on just one vine and babies the heck out of it and feeds it a ton of fertilizers to get it to grow huge. That seems like a ginormous amount of work for something you're not going to end up eating. It's purely for bragging rights really. Me, I'm practical, I like to eat what I grow.
We got some interesting squashes this year on a drive out to the country and I particularly loved Musquee de Province, a very large flattened pumpkin with fluted sides. It's absolutely gorgeous to look at, green and burnt orange, but the flavour really impressed me. It's got very dense, dry flesh and a lovely sweet flavour. I canned cubes of it in water using my pressure canner for use in recipes all year long. That one squash provided us with a case of litre jars of cubes. I have one more squash to use this winter and I have no idea which variety it is. It's again, just gorgeous, a pale salmon colour with white netting all over it. I've really gotten into the non-bright-garish orange squashes and this year I'm contemplating growing Jarrahdale and Triamble squashes. I'll be happy if they get to the size of an average dinner plate.
Good luck with your Big Zac F1, Derek. I grew it last year but the weather was really underwhelming and we only got a couple, not even 2 lbs per fruit.