Weight, Clamp or stabilizer?


I have a vintage Pioneer PL-560 Direct-Drive Automatic Turntable purchased around 1980. 
https://www.vinylengine.com/library/pioneer/pl-560.shtml
I'm trying to get it to produce the best sound its capable of.  I plan to order a set of SVS subwoofer feet to replace the worn feet (I have an SVS subwoofer and removed its feet and temporarily placed them on the TT base with good results).  I read an article about TT tweaks.  A few things they suggested were an upgraded mat, clamp and isolation feet.  Thing is since the TT is a direct drive I don't know how much extra weight it can take (if any), and the spindle is about 7/8 inches tall so I don't know if that's enough for a clamp.  The original rubber mat it came with is in great shape. Do I need to replace it, too? I'm willing to invest in tweaks to improve this turntable, but not interested in replacing it.
mewsickbuff
I am interested in the questions from the OP. I also have a vintage Pioneer table (PL-530) I bought new in the 70's. Have used different cartridges over the years and am now using a Grado Gold.
Aside from playing less than flat records I have an interest that pertains to the table feet. The feet on the PL-530 are just plastic ones that have no isolation capability. But most important, there is no adjustment for leveling the table to a close to level state.

My question to those who may have experience with these vintage tables.....My house is well over 100 years. Floors are anything but level. To obtain balance of the table I have used thin shims on each of the 4 corners to achieve as close to level as possible. Besides the capability of isolation, does anyone know if feet with isolation properties as well as adjustment for height available??


@jrpnde
Besides the capability of isolation, does anyone know if feet with isolation properties as well as adjustment for height available??


One of the best isolation device is Audio-Technica pneumatic insulators AT-616:

Set of 4 supports 10 to 60 kg (22 to 132 lbs.) and each one is adjustable. They are big and heavy, can be placed under turntable or any audio device including subwoofers. Also can be placed under wooden platform to make the whole table isolated. The 616 model was the best and most expensive, they made cheaper alternative, but cheaper AT feet can’t support heavyweight.