Phil,
Good question. First, let me say that the SX-28, although entirely
collectable and one of my absolute favorites, is a certifyable bear to
re-cap, especially the straight SX-28. Given that you're a professed
neophyte, you might want to hold off on that one unless it already been
accomplished and is running OK. The Hammarlund HQ-140 and the 150 are
excellent, yet fairly simple, receivers, very easy to work with and on,
and are quite affordable. All parts are accessible and readily
available, if necessary. The more modern HQ-145 and HQ-160 are also very
fine. The SP-600 with disc caps is fine; the one with "black-beauties"
requires (albeit at worst) the changeout of over 50 caps, some well
hidden and requiring some disassembly of the receiver. Again, I'd
recommend either the Hammarlund HQ-140 or the 150 as a starter.
Regarding Heath and other kits.. At the risk of offending some folks, I
don't know of a decent general coverage kit receiver I'd care to own. I
do have my original Heath AR-2 but its a poor receiver. The other
crapshoot is who built it to begin with. Any kit, Heath or others, if
built by a newby using their uncle's 300 watt American Beauty soldering
log will (or may be) a disaster. You really need to have a look inside
ANY kit unit to see the quality of construction. But.... this is my take
on "several" years of doing all this. Make your own decision....
Regards Jeep/K3HVG