Nice to see that you are calculating things, but coils don't work in the same way as steady state resistors.
Current rises rapidly in an inductor:
So to work out the correct dwell you'd need to calculate the amount of spark energy that the plug will need to fire, then work back from the secondary coil to the primary - so you'd need to know the number of windings as a bare minimum then factor in loads of stuff I dont understand.
But what we find in reality is that we use a rule of thumb for these sorts of things - Coil on plugs usually take 1.2 to 2ms, coil packs 2ms to 4ms, single coils with distributors tend to take more (never done one so I can't comment).
The tuning process is to start low and see how you get on - with a coil pack like you have I'd go for 3 to 3.5 and try increasing 0.25ms at a time if you don't get a spark (Ford EDIS coilpacks need 3.8ms before they spark) once you're running you may find some high RPM misfires occur if your dwell is too low, once again you can increase the dwell a little if this happens.
Most importantly you need to use a fuse to protect things if you use a 6 to 7A fuse you shouldn't burn out anything that way.
