IRL Race Prep - Which Zwift Training Program?

Hi all,

I have a 100k gravel/mixed surface race April 30 2023 I’d like to do some focused training for. Assuming a January 1 start this is 17 weeks till race day.

I have a decent fitness base, weekly average training load of ~450 (per intervals.icu) over the past 10 weeks. This is from ~3/4 rides and ~3 squash matches/sessions.

Riding 100k is not the challenge, as I can go out and do it in my current Z2/Z3 no problem.

Will still need to play squash 2x a week, but matches will vary in intensity from easy-ish 30min to hard 60min, so can work a rest day after if need be.

Which Training program(s) would you recommend?

Start with Gravel Grinder 8 weeks and then TT Tune Up 8 weeks? Or would Grand Fondo for 8 weeks better given my race distance?

Thanks look forward to input.