Need Source for New Brass Seats for 65 Power Brake MC

[Mike T.]

I added Power Brakes to my 66 Coupe back a few years ago. At that time I figured I'd start assembling the necessary parts to do the same mod to my '65 Coupe that had been in storage since '90. Well, I got the 65 back on the road and figured I'd get to that PB installation now.
I happen to have the original power brake master cylinder that used to be on my Dad's 65 Coupe. Back in the early 90's we sent it to SSBC to be sleeved and rebuilt but we wound up using a 67-later version Master instead and just shelved that original MC till now.
The existing brass seats were a little dinged up so when I was ordering parts a few years ago I purchased new ones from Long Island, part #52-19R, listed for 63-66 STD and 63-66 PB. Tossed them in the drawer with all the other parts at that time. Yesterday I figured I'd install the new seats. Got the old ones out and then...realized that those replacement seats are larger than the ones in my 65 MC and won't even drop down into it.
I know the basic difference is that 65 PB units used the smaller 3/16 brake lines while the 66 PB's used the larger 1/4-size so I'm guessing that these replacements are for the 66 PB versions.
Anyone know of a source for new brass seats for the smaller sized 65 power brake master cylinders?

Thanks,
Mike T