Hello all, I have a couple of questions that maybe someone on here might have a couple of answers for.

I recently picked up a 79 3/4 ton extended cab 4x4 that has a really nice flat bed, great paint, and is in overall very good shape and I picked it up for a great price. The engine, a 400, is running but getting tired and of course not much of a powerhouse. The reason that I got the truck for such a great price is that the tranny's 3rd gear was shot, so for $175 I put a junkyard 435 in it and was good to go.

Mostly the truck is a work truck. I can load up dang near 2 cords of wood on that flatbed and slowly poke my way down the mountain. I live in Montana, so in any direction I drive I have mountain passes to go over. I want the ability to pull a trailer when the need arises, to be able to haul a heavy load up and over mountain passes, and just as an all around work truck. So, with that said, let me throw some ideas out there on the engine build that I'd like to go with.

I'd pretty much planned on building up an engine with Aussie 302 heads, Tim Meyers pistons to go with those heads, a toque cam and the valve train to go with it (one Tim recommended), the Edlebrock intake, and most likely the Holley truck avenger carb, but the carb is still undecided. In other words this is basically the "400 rebuild kit" that Tim Meyer sells on his website. I had spoken with Tim himself explaining what I wanted to do and explained that I wanted something that I could run pump gas in without any detonation. He assured me that this combo would work for what I was wanting to achieve. I had it all planned out, it was a done deal. Then I talked to the machinist in Bozeman who was going to do the work for me. He tried to talk me out of it. Now, he's not just some machinist, but he's got an excellent reputation throughout this area for really knowing his stuff. He was sure that under the conditions presented to him that this engine would suffer from detonation and even just a little detonation would destroy those hyper pistons that Tim has Kieth Black build for him. He said something about the top piston ring being too close to the top of the piston head. I called the tech at Kieth Black. He agreed with my machinist and said that running low-octane fuel and pulling a trailer/hauling a load that I stood a good chance of detonation even with a conservative initial timing.
So, my question for you guys who have built this engine, have you had any problems running low octane fuel and towing/hauling? Do you have any recommendations?