If you're level, it's not as much a problem as you might think. Assuming your convergence is all set the same, they'll all get to the same place (just not at the same time). If you're pulling lead and making Gs it's a big issue. They'll drop significantly. MGFF less than 30mm, but still significantly.
The inboard MG151/20s on all 190s are decent. They are not hispanos, and depending on what other planes you normally fly, you will need to lead 2x your normal distance (or more, depending on situation). These guns are quite common in AH, found on almost all 109s, all 190s, the 110G, the ar234,the C205, and some similar weapons that may or may not be based on the MG151/20 on some Japanese planes.