Welcome-----If I remember right, isn't Eagle River uphill from Ancorage??????????Always was amazed at the glaciers flying into/outta Ank and Fairbanks-------

For a pure dollar choice, staying with a small block 350x would make things such as mounts, exhaust,etc simpler----if you are considering straying from sbc I would suggest taking a good look at a lift out package(engine/trans/accessories((alt, ac. ps))
of one of the late model trucks---example--5.3 with auto overdrive trans---fuel injection---economy and performance plus drivability will go way up---and it will adjust for the altitude differances as you climb the hills----