I have the bam rollers and 456/461 lobe lift. The oil bands don’t come out of the bores in a ‘77 360 block. Your lobes are a little shorter, so you are likely to be good. As was said, you’ll need to check of course since “every build is different”. My custom solid roller from comp came out to $620 (2 years ago), so your pricing isn’t too far off.
You’ll want to invest some more coin (~$1,000) in a good custom converter to match up with your combo and you’ll likely love the way it pulls... it’ll help to ignore whatever’s lost on the low end, and that one will lope nicely. Also invest in a good trans cooler.