I run EFI on my '70 Challenger and love it. I passed through your neck of the woods on a road trip IL-CA-IL not too long ago. It did great in the mountains and deserts. No issues at 7,500' and 32F and 0' and 95 F on the same day.

As far as fuel supply, I had earlier tried a stock type tank and frame rail mounted high pressure pump. That was a no go. The pump was noisy and worse than that failed twice. High pressure pumps do not like to suck. I went to an in tank pump. In tank pump or remote sump with low pressure pump feeding the sump and sump feeding the high pressure pump is the way to go.

There are a number of options for in tank pumps including a modified OE style tank. Remote sumps can be purchased or homemade. If you go EFI I would strongly recommend one of these options.