need crossover help

I have a 416 8b in a 12 cuft cabinet with a 808 8a driver mounted to a 400hz tractrix horn the tractrix horn is shorter than the 811 so i can line up the voice coils without the horn sticking out past the front of the cabinet. so if i go to a model 19 crossover can i keep the voice coils in line or will this effect the crossover? iam told the mod 19 crossover is time aligned and that changing the distance between voice coils will effect the crossover is this true? also looking for a place that will use calsod or leap to design my crossover i contacted madisound and was going to ship my drivers to them but my money and my request was turned down! i take it they dont like vintage drivers or they just want to sell crossovers for speakers they sell. anyway any advice on the crossovers would be great thank you.

Nothing beats proper testing. I assume you have signal generators, if not you can free software with a soundcard to create the tones.

If you start with stock values you might be able to tweak them a bit and check the overlap at the crossover between the horn and the bass. If they were mine I would use a RTA to check the response first and after every change to plot what is happening.

The time alignment is important but that is only small part of crossover design. The drivers have very different dispersion patterns and the crossover affects the pattern. Above and below the crossover point both drivers are reproducing the same tone, with different dispersion and sometimes different output levels. The trick is to balance that transition so you don't get a peak or a null in response. Checking with a microphone and sweeping the system will tell you if you have either. Checkng at differnt angles will give you some idea of the intereaction between the two.

Your using a well known combination of drivers. I would also consider using someone's design and deciding if you prefer it to what you have now. Reinventing the wheel takes a long time and crossover parts can be expensive.

Enjoy the journey, this is what audio used to be all about