Strength, current 5 min (strava) power is 393. If I can increase that by 10% or more and come close to 450, in combination with the weight loss I'll have a power to weight ratio similiar to the other riders that are achieving the time I have in mind.
Generally speaking 5 min power of 393 is a lot. Unfortunately, Strava's 5 min, if you're referring to its "5-min/10-min power" entry in your profile, is easily misled by wind and poor terrain data. You have to use a power meter or figure it out manually. Looking at a couple of your recent rides, I see a 1-min effort of 580 W, a 4-min effort of 365 W and a long sustained effort of 280. That should put you around 350 for 5 min. Which would still be very respectable for an average size rider.
Your problem seems to be that you're really big. I'm guessing ~110 kg? If I had your power and my weight (70), I'd probably be in the top 5-10% of serious recreational cyclists in this area and approaching pro level. I don't know how tall you are, but there's almost certainly more than 5-10 kg to lose. (And I suspect that it would be a lot easier to lose more weight than to bump the 5-minute power to 450.)