Phantom custom mount on SME slot?

I currently have a Graham 1.5T mounted on a VPI TNT using an SME type mount. There is a Phantom with the Graham custom base available to me and I'm trying to determine if the custom base could be used on my current armboard with SME cutout.

Centre of the SME cutout is the same as the custom base ~8.5" from the spindle and width of slot is about 30mm.

Thinking it should be possible to mount over the SME cutout and just drill the new holes required by the Graham base.
This would save me getting a new armboard in the short term.

Wondering if one of the forum's Phantom owners, with Graham custom mounting base, could measure the diameter of the base and the distance between mounting holes?

Also interested in any opinions on whether the Phantom Custom base is better/same as SME mount sound-wise?
I have VPI and Graham TNT armboards cut for SME & Graham 2.X respectively. I believe the 2.X pattern is same as Phantom? It's not practical for me to overlay these armboards right now, but I looked at it awhile back. Overlaying the Graham cut-out and drill pattern on top of the SME pattern is feasible but unsightly. The Graham pattern is a 40mm diameter hole encircled by four drill points 40mm apart. The SME pattern is approximately 70mm x 32mm elongated hole with four drill holes at corners 60mm x 42mm. My recollection is that none of the corner holes line up.

You'd probably have better luck starting fresh with a used Graham armboard for about $200 or a piece of 11" x 4" hardwood. Alternatively you could cover the area with a 1/8"- 1/4" brass plate.
Just email Bob at
Or call him phone: (781) 932-8777.
and ask he will help you.
I've pretty much decided to go for SME mount Phantom. Saves the hassle (and expense) of sourcing a S/H Graham drilled armboard. With the demise of the TNT, armboards no longer appear to be carried by the online retailers either.

Thanks all for the input.