You can read a brief post about how ship to ship shooting is calculated here http://kbismarck.org/forum/viewtopic.ph ... 25&p=18594
As you said, you have simplified the problem, because you are stationary. You only had to compute enemy movement, getting course, speed, bearing and range, all from radar. One problem of calculating this manuallly, is that the deflection (deflection in degress = speed across / range, see the post above) varies continuously, because speed across depends on target angle (angle between bearing to the target and its course), which varies continuously too, along with the range. This is the reason why to solve properly the problem, you need a rangekeeper that continually recalculates the problem as the paramaters vary. Anyway, with the method you were using, and correcting to fall of shot, you are technologically with an about 1915 fire control system.
What remains unclear to me, is how did you manage to "harmonize" radar beam and gun (make the radar beam converge with the firing line at a determined distance). I understand that with triangulation, you can determine, from the target´s and gun´s bearing as seen from the radar, an angle for the gun to aim to the target. The question is, this angle must have a point of reference from where to start measuring the angle. What did you use? True North? Magnetic North?