EFI Fuel Venting using Vaporworx GM Module and IIMuch

[GoldHawg]

I have an older Datsun Roadster that I am upgrading with modern everything and for the fuel system I plan on running E85 since the Autech engine I have is almost 12:1 compression. I have already purchased the SS ring from vaporworx to mount a Camaro V6 fuel module, which should both be able to handle the E85 and also support the HP rqmts (~200RWHP). The tank will sit a bit more than 1" down from the trunk floor, so I don't need to build a recess in the tank and I'm following the rough shape of the stock tank which gives me ~ 11 gallons. I will be cutting out the section for Carl's SS ring as seen by the sharpie mark. My question is how to handle the venting on this tank. I wanted to go with the IIMuch system, even though they don't warrant for E85, but their detailed install instructions say that you have to have a domed portion of the tank to allow expansion--a dome which I don't have (and most tanks I see others building online for EFI don't have as well). Other installs just put the vent port on the top part of the tank somewhere. The stock tank cap is vented, but I know I at least need a nipple or something when fuel is added to relieve the pressure. I'd like to minimize gas smells, which is another reason I was considering the IIMuch system. What's the real requirement for venting? If I can't get the domed part of the tank (not happening in my application), what's the next best solution if I can't go with the IIMuch system? Does it matter where the venting will be as long as it's on the top (i.e., is it better to be near the filler)? Thanks for your recco's.