If I recall correctly, the F-1 had not even the MG 151/15, but still the old MG/FF. the 151/15 appeared with the F-2. The F-4 (and re-equipped F-3) were the first ones with the 151/20.
BF 109 F-1/R1 had gondies
You (or your source) are confusing it with the F-4/R-1 - our F-4 with gondolas.
An F4 with gondolas was a very rare bird