Manual macro lens and extension tube

Hi

I'm looking for a macro lens and considering what I do and how much I do it, one of the older manual focus lenses seems like a great option. I don't shoot bugs or anything like that and mostly shoot small parts of musical instruments.

I understand the older lenses are not 1:1 magnification. Does anyone know the magnification of these lenses? I'm referring to the 55mm f/3.5 AI, 55mm f/2.8 AIS and the 105mm f/4. I'm leaning towards the shorter one for more DOF and lower price (this lens won't be used for anything else since I already have "faster" lenses for non-macro in those ranges).

I also see some tubes that make them 1:1 but there are many models and I'm not sure what is what. M2, PK-13, PK-3, PN-1. I considered a Kenko tube set but that makes the entire set a bit too expensive and I'd just get a true 1:1 lens in the first place. Something like 1:2 is really not enough for what I need.

In comparison, my option for a current macro lens is the Tamron 90mm which is on sale for around $460 (normal price here is $600). Nikon 60mm D is another option for a bit more and the G version is significantly more. With the Tamron I'm worried about sacificing too much DOF (same with the MF Nikon 105mm)...

I have a friend who is visiting from USA soon and it's a great opportunity to buy from ebay.

Here is an example of the type of macro I'm shooting. Screw is just over 2mm dia x 2mm lenth.

Thanks!