Awesome Express you found! Really is a beauty. Looks like she was already very nicely custom outfitted by a serious fisherman before. That's a lot of nice gear still on there. Jealous of that super sharp looking hardtop! That must be so nice for getting out of the weather and keeping the console area nice and dry. Such a cool looking yet also practical layout in my opinion. Looking forward to seeing more pictures of her, especially the inside. Does the boat have a name yet?
Those canvas pieces would probably be hard to find new. Since you have old ones I'd just take em to a top shop and have new copies made from those as templates, nice simple pieces like that should be very easy for them to do.
The floors on these aluminum riveted boats couldn't be easier to replace. 3/16 drill bit and some gloves and you're ready. The hollow core aluminum pop rivets in the floor drill out very easily- they already have a pilot hole! Cheaper non cryo hardened basic old gold looking drill bit is preferable, they flex instead of snap if they bend while drilling. Careful of depth. Once you do that you can just pull the old floor right out, section by section. Great opportunity to check for any old loose rivets, do a really nice cleaning under there, find old lures lol, refresh the Styrofoam with new blocks if it's bad, add a nice easy wiring pathway or two for future add ons, and then refloor with fresh ply and she will be like new in there for another 20+ years easily even if all you did was seal and paint the plywood really well! If the old floor pieces come out mostly intact it makes for an extra quick copy and replacement job. I went from the factory 1/2" plywood to 5/8" bcx in my Chieftain and thought it added a lot of nice rigidity under foot with very little weight and fitment difference, vs going from 1/2 to 3/4.