I seem to be on a similar path as you were at a little over a year ago with putting together a 8510C system with 8341B source.
What are the devices in your setup now?
Did you ever get the right PAL chips?
Does the entire system work now?
I am really interested in any experience you gained on your way as I do not have fully functioning system as of yet.
I only have the PAL allowing for v.7.xx at the moment but I am interested in adding a 8530 and time domain functionality later on when I find them.
Quite a bit has changed in my setup from last year. in terms of individual parts I now have ....
3x 85101C Display unit (one is a spares unit, one only has the 8510C & option 010 PAL chip, and one has got all the PAL chips)
2x 8510C Receiver unit
1x 8530C Receiver unit
1x 8515A Test Set
2x 8514A Test Set
1x 8511A Test Set
1x 8341B sweeper
1x 85309A LO/IF Distribution unit
2x RF Interconnect cable (genuine HP)
2x Data cables (one HP one generic)
1x Set of 40GHz Rosenberger test port cables
So that breaks down into (almost) two systems
A basic 8510C VNA system
85101C
8510C
8515A/8514A
8341B
And an 8530 antenna range system
85101C
8530C
8511A
8341B
Obviously the 8341B is shared between the two systems at this point, and I haven't found a use for the 85309A yet as it requires a few extra bits like couplers and mixers. I updated the firmware of my 8341B from '88 to '92 which apparently improves some bugs and glitches. And all my BNC cables are genuine HP too. Getting the various boxes together is the cheap and easy part (believe it or not). It's all pretty useless without a proper cal kit with verified values loaded into the system. And you need decent phase stable RF cables too, ideally test port cables. Neither of these things are cheap.
v7.xx is the latest firmware for the 8510 VNA with a CRT screen, higher than that and you need an 85101C with an LCD screen. Nothing to do with the PAL chip.
The 8530 latest version firmware is lower, 3.xx or something ? and this is just for antenna range testing.
I can't remember all the configurations for the PAL chips. It's documented somewhere though. I think all of them with run v7.xx VNA firmware using the one PAL chip that they all come with. The extra PAL chips are for Time Domain and the 8530 Antenna Range firmware. I think! you'll have to check that though, it's been a while.
I replaced some of the fans, notably in the 8341B and it all runs pretty quiet, certainly much quieter than the HP3335A I've got.
I've also got an 8753C with the 6GHz option. And to be honest I use that much more than than the 8510C.It technically probably isn't as good, but it's a lot quicker and easier to setup and use. Not to mention takes up less space.