Compatible parts for my vintage Holdsworth

Hi there. I recently completed a 8000km tour of europe on my vintage Holdsworth Monsoon. Now that I am back home I need to replace several well worn and tired parts.
The most urgent is a new chainset to replace the Stronglight49D that I have on tat the moment (the extractor thread is stripped, the chairings bent and hard to find). I have been considering buying a compact chainset, but would that mean also having to buy a new front mech too, or could I use my Shimano 105? the most commonly available chainrings seem to be for 8 to 10 speeds, but I am running only a six speed freewheel, will this be a problem? But this doesn't matter to me so much because I was contemplating buying a new rear wheel anyway with a cassette hub (130mm between dropouts)... but would my Shimano 600 rear deraileur be able to accomodate the new range or will I be replacing that too?
Which is a good rear hub for loaded touring? is there any advantage to non aero brakes (aside from being more "vintage"), will our hero escape this minefield of bicycle dimensions, will I end up replacing everything but the frame?
So many decisions! Thanks in advance for your suggestions.
Peter

You CAN change the chainset and/or BB and continue to use the rest of your exising components ...

The ONLY type of chainset/BB which I suggest you avoid are the ones with ISIS bottom brackets.

I think Octalink are reliable, others disagree.

The BBs with external bearings do have some reliability issues, but they are considered to be the current standard.

Square taper BBs are still considered to be fairly reliable by most people ... the mating tapers on the cranks can be damaged if they are mishandled, of course ... square taper cranks lack "sex appeal" which many riders want their bikes to have AND square taper BBs are often crank-type/(generation) specific.

If you don't change your shifters, you can continue to use your current derailleurs. If you opt for new shifters, you will want to buy new derailleurs because the width of the pulley cage on the pre-8-speed derailleurs is too wide to avoid the derailleur cage interfering with the spokes when the chain is on the largest cog.

Generally, with indexed shifters, the front derailleur should match the chain type ... the chain should match the cassette/freewheel. Basically, an 8-speed chain can be used with anything from 5-speed to 8-speed bikes (Shimano's 8-speed chain is a direct copy of the old SEDIS NARROW chain ... SACHS bought SEDIS ... SRAM bought SACHS).

I have been using "Alpine gearing" for decades and have always preferred to use a front derailleur designed for a triple when I have the option BUT many people suggest that you can use a "regular" front derailleur with BOTH a "compact" & regular crank ... and, I have also used a regular front derailleur with a "compact" crank when I didn't feel like changing the front derailleur ...

The potential problem with using a regular front derailleur that is intended for a "regular" double on a "compact" crank is that the chain MAY (or, may not, of course) drag on the back edge of the front derailleur's cage when the chain is on the inner chainring + some of the smaller cogs.

ALL Shimano hubs are good values ... if you are going to stay with a 6-or-7-speed "friction" (?) configuration, then you can opt for a Shimano ACERA hub which has a shorter freehub body that is intended for 7-speed cassettes. The Acera rear hub is designed for frames with 135mm rear spacing, so you will want to remove the 4mm spacer from the non-driveside & shorten the axle to use it in a frame with 130mm spacing.

If you've got a ton of money, then DT 240 (or, 340) hubs are a very good choice.

NON-AERO BRAKE LEVERS. The advantage of non-aero brake levers is that you can wrap the handlebars more quickly AND you can change the brake cables more quickly. The disadvantage opf non-aero brake levers is that effective braking is only done from the drops.