Thank you all. I am thinking the "attachment issue" can be resolved by using cable ties while winding the cores and then replacing them with cable ties to anchor the cores to a "platform" which in turn is bolted to the box.
The usual construction uses a waterproof box so "ventilation" is pretty much self-defeating. I've had experiences using ventilated boxes with the vent holes covered with super-fine mesh. It's amazing how many super-super fine critters live in your yard! Then there is the moisture problem, even with the two recommended very small "drain" holes in the bottom.
While existing designs are rated at 250w, most operators will be using 100w max. So heat shouldn't be a problem.
Unfortunately, I've been influenced by the philosophy of a hot-rod builder that lived over in the "holler." That was, "If'n 300hp will do it, 600hp will do it better!" In this case it's just adding another core and I can QRO. It's just as easy to install a 4 carb manifold as a two carb.(Please, gear-heads....stay with the subject!

IQ: #16-#18 noted.
VT: Glass tape info filed. Thank you both.
Al - K8AXW