Hey,
What is the spindle to centerline of the post/existing hole distance in mm?
Next question: is that tonearm board reversible, i.e. rectangle, spin 180 degrees?
I cannot tell if it is a simple rectangle with the spinner overhanging above, or if it is shaped around the spinner, thus not reversible. JVC does both types, it makes a difference.
IF reversible, For my very long arm I rotated/modified my right side board, new 304 hole, and put a 45 rpm adapter in the old 270mm hole so it looks designed rather than a mistake. Later, I changed to a UA-7082 arm, spin 180 degrees, used old 270mm hole, covered the 304 distance hole with a small level I leave on the plinth.
The rear board, I needed to enlarge/ease the existing hole 3 MM in one direction (fit 225 mm in an existing 222 hole) for the slightly longer spindle to pivot distance, knowing the base plate would just cover the slightly elongated hole.
The left backwards arm is just a hole (no removable board), for a small diameter post of a mission arm with a Jelco surface mount.
Next, I changed that arm to an alternate version with a removable headshell. I again had to ease the hole a speck to fit, and again, the baseplate covered the elongated hole.
AND, the base plate had to not hit the wide rim of the TT81 spinner;
AND, the short counterweight had to fit within the dust cover when on,
AND the height of all 3 of the gimbals all had to fit under the dust cover when on.
Whew, I never mounted an arm before this, and the long arm’s height, when raised up with a spacer, LUCKILY just fit.
here it is after the change to 3 removable headshells
that’s not dental floss, it had a bad wire, VAS rewired it, I wanted to remember that.
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Small Diameter Post is an advantage if/when changing arms of slightly different lengths.
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Under the arm board: you need clearance if a fastener below, and to get a tool to tighten it, so check, my friend has a plinth like mine, and the holes are machined thru several layers.
My friend's Luxman PD444 the arm boards slide and lock in a track. One of his Micro-Seiki 505 Arms was missing a washer for the nut underneath. We found one a bit too wide, and had to grind off the width on two edges so it would fit the track width.
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If someone helps you, be extra cautious. I just helped a friend mount an arm.
I told him we needed a 1" bit to fit the 29/32" post. Figuring, like me, he had a 1" bit.
Across the room, with music playing, he asked me if 29 mm bit would work. I heard 29, and my mind thought 29/32" so I said, yes if you wobble the bit to enlarge it to a 1" hole.
OMG, he drilled 29mm, too big of a hole, and the base plate was very small, a speck of the hole was not covered. I was horrified, and felt it was my fault, still do.
Luckily, he is quite a craftsman. I had brought some hardwood, he made a circular hardwood bushing to reduce the hole diameter, had some fast drying light colored bondo. It dried while we went to lunch, you cannot see the speck of bondo on the light pickled oak plinth unless you know to look for it.
I still feel guilty, but we finished, mounted the Benz Micro Ruby Wood SL cartridge I had VAS re-tip for him, and it sounds better than any cartridge he owns (I broke it in here).