St. George 70.3 Sub-5 Training Plan

I'm signed up for St. George 70.3 and I'm trying to figure out a training plan to go sub-5 there
I've been triathlon training for about 2 years now and have placed or won my age group at most of my races (which have all been Olympic distance).

What would be the general time/workouts needed to get my 70.3 time below 5 hours?

Some more information about my background
My strongest discipline is running, most recent half marathon was 1:20

Swimming comes easily to me, I'm usually one of the first out of the water at my triathlons (Olympic distance swim takes me about 23-25 minutes)

Biking is my weak point. I ride a specialized s works tarmac sl3, I usually get caught on the bike but then make up time on the run

Open to any advice