Hey Craig,
Process I used for my Type 65 to get reg on Mar 1 2023 in Smith County south of Tyler in Troupe.
1) download Motor_Vehicle_Registration_Manual_Book_298 read it, know it.
2) get a weight, went to scrap metal recycle in North Tyler $10.
3) Got insurance and proof, Grundy.
4) download and fill out VTR-852 (need for next step) & VTR-61 forms, from TX dept MV site.
5) Chassis inspection by ASE Master Cert Mech in North Whitehouse (south of Tyler) $220
6) Five Photo set: Front, Back, Left, Right and frame SN.
7) packaged ALL receipts for the build, to show I have already paid a bunch of TX sales tax.
8) FFR manufacture cert, should have come with your parts pile as a final delivery.
7) Take package of everything listed above to MV Dept.
I did a custom car build registration, mine took about 30min to get done,
Clerk had never done a custom car build before and had to call another office to get help.
Make sure to let them know about all the sales tax already paid and that you would be willing to review all the receipts.
Very big pile and they opted to take my word.
Only issue I had was they wanted me to get a standard inspection, I had to educate them that the VTR-852 covered that.
Got out of there with a total cost of $100.
If you are in a smog county then there might be more hoops to jump through.
I'm in the sticks, we don't have any hoops.
Hope this helps