I never had any experience with the GR-54, but I had a Heath GR-64 when I was a kid in the late '60s. Listened to a lot of shortwave on it (that's part of what got me interested in shortwave enough to eventually get a ham radio license in 1972). My GR-64 is long gone,
but I had lots of fun DXing SW and even the broadcast band while I had it. Had a bit of a disappointment when the power transformer burned out (I don't remember what caused it), but I was able to get it working using a couple of outboard transformers until I got the right part from Heathkit. The radio was working so well with those outboard transformers sitting next to it, with a cable running back to the radio itself, that I was in no hurry to replace them. But eventually I got the new one; I must admit, the radio looked 1000 percent better with the transformer on the chassis where it belonged! Oh yeah!
I know what it's like to get a radio or TV minus the tubes and other parts (in your case, the knobs). I once had a 23" Zenith b&w console TV I picked up on a curb in my hometown in 1969. When I looked in the back of the set, however, I noticed all the tubes were gone, with the exception of the HV rectifier and CRT. I retubed the set, though, and was rewarded with that great Zenith picture on all three network stations from Cleveland, both on rabbit ears and on the attic TV antenna in my home at the time. Unfortunately, I had to move in 1972, as (bad) luck would have it to a house with no room for big console TVs, so I wound up putting my nice Zenith--which I had spent so much time retubing/rebuilding (I had even patched in an FM tuner to take advantage of the set's excellent 6BN6/6BQ5 audio stage and 6x9 oval speaker)--out with the trash (from whence it came in the first place; what goes around comes around) about a month before I left town.
I didn't even get the practically new tubes out of it before putting it on the curb in front of my former home.
! Nearly broke my heart to part with that set after all the work I'd put into it, but I had no choice. It would have been nice to at least salvage the dark wood console cabinet, but...oh, well. I have six Zenith radios today, however, which sort of make up for getting rid of my Zenith TV almost 34 years ago. You can be sure I will not part with those radios if I can help it.