Did you check the other catalog numbers for this piece as well?
Concerto C-Dur (do maggiore) F 1 No.135 - T 311 - RV 187
It was published by Ricordi (G. Malipiero ed.) in 1960, apparently only as a score (and that would imply parts are rental).
Should still be available, with all the caveats about the management of Casa Ricordi by the new owners Sony-Universal Music.
In the Ricordi online catalog I found it only with the T 311 and F I - 135 numbers:
Antonio Vivaldi
F. I n. 135: in Do magg. per Vl., archi, Cemb. T. 311° (G.F. Malipiero)
Numero catalogo: PR 961
You can also find the score in Vol 25 (Tomo 301-314) of Opere strumentali (Istituto Italiano Antonio Vivaldi) Ricordi 1960
I found it here for sale
http://www.alle-noten.de/ Best-Nr.: ERPR961 (no description, I guess it is the score) ships in 1-3 days
and for the US Hal Leonard HL 50033490 (special order import item) score only
I could copy the score, but with Malipiero as editor this will most likely be off limits for imslp