Welcome!
If the tank is being drilled now (or soon) I'd focus on that straight away.
I'd ask for a bean animal-style overflow and for at least two return ports. Are these things absolutely necessary? No, but you have the opportunity to do it right now for minimal expense. Also, pay particular attention to the overflow box. That's personal preference, but get what you want. Gate valves for your primary drain(s), not ball valves.
Next would be the stand. There's no reason it has to be the exact width of the tank. Even an additional 4-6" on either side can really make a world of difference.
Last thing I'd give hard thought to while the woodworking is being done is if you want a canopy or not. It' a different look than the en-vogue, ultra-modern. However, it's way more flexible. It opens up a much wider range of lighting options and mounting heights and lets you hide a lot of your uglies like auto fish feeders, tank covers, powerhead cords, cooling fans, etc. In no way saying you need one, but consider it now while your friend has the saw and the sandpaper ready. It will impact your equipment choices considerably.
With a solid foundation, you'll be able to enjoy (and upgrade) this tank well, well into the future.
Only other tip would be to stay modular. Two smaller, cheaper return pumps over a pricey one (perhaps, that's my preference) and multiple smaller lights over a single fixture. This way things work on this setup and the next.