Air taxi helicopter pilot reported JFK Tower issued them a clearance to cross Jamaica reporting point at 500 feet which placed them in unsafe proximity to newly constructed buildings. The reporter could not verify their clearance with JFK Tower due to frequency congestion.

Narrative

Flying eastbound from JRB to ZZZ via helicopter TRACK route with class B clearance from JFK Tower; [frequency] XXX.X. Normally when JFK is landing Runway 22; clearance issued is maintain 1000; cross BELMONT at 500. On this flight; the clearance issued and read back was to cross JAMAICA station at 500 ft. Upon realizing this clearance didn't seem to allow for adequate separation from the newly constructed buildings charted at 386 ft.; I attempted to contact the Tower but due to frequency congestion was unable. Also there was another helicopter traffic behind us that we had on TCAS but not visually; so slowing or turning around was not practical. We had to deviate south of course and up to approximately 700 ft. (about 200 ft. above clearance limit) to maintain a safe distance from obstacles. There was no traffic above; and we were an adequate distance west of the Runway 22 corridor with no other traffic in sight. After safe passage; we immediately returned to cleared route and altitude without further incident.Due to the ongoing frequency congestion; was unable to discuss with JFK Tower; they made no mention of it either. Also I attempted to reach the Tower by phone to discuss; but both numbers were constant busy signals.I have traveled this route often; and have never been issued a clearance limit of 500 ft. at JAMAICA. Also it seems that either the buildings are higher than charted or there is an altimeter discrepancy between JFK and that area. I think 500 ft MSL is too low for safe transition in that immediate area; going forward I will not accept that clearance and take an alternate route if that is to become the norm.