Grant,
Masis have always been available from 48cm C-T to 64 cm C-T in 1 cm increments. 65cm Masis exist but no "fixturing standard" frame hung on the wall at Masi in the early days. I have a 1962 Masi Special in 50cm, which is a very rare thing to find in a bicycle of the period except from someone like Masi. You needn't question Masis' greatness; it's real.
If one wanted a 53.5cm (or for that matter a 53.7cm ) frame from Masi it could be had for the extra charge, whatever that would be. Convincing them it was neccessary might have been a chore, but money talks! Masi could do it if you wanted it. Hope that clears that issue up for you so you can proceed to fall in love with these classics; unless of course you ride a 50cm or so. In that case buzz off, I want it!
Brian Baylis La Mesa, CA According to Peter Johnson "there's no such thing as having too many (classic) Masis". Or maybe that was me, but we both agreed.