For a semi cab-forward body, and not looking over the top too modern, the JConcepts Finnisher - T4.3 Qualifier Series body 🤘 :cool: 🤘 would be a direct fit.
BOKI Racing reproduces a couple different bodies (Crowd Pleaser & Interceptor) for the T4 as well.
I personally have not done the swapping of the "5 series" caster/steering blocks & axles on the "4 series" T4, but the eBay chop shop for such parts is here... https://www.ebay.com/itm/313306544277
Just be aware the ball studs are larger, and would need to account for that as well.
I'm not...
If you want to do a hex conversion on the front you'll most likely have to buy a roller for parts, or mod something to work. The stock 7854 hex axles are just not out there. I'd look to Pro2 SC10 eBay chop shop caster/steering blocks/axles to install. This is what the SC10 users are doing....