There are a thousand different choke set ups out there. You might attach some pix and the numbers will also be necessary to find you what you need.
BTW, you may or may not care, but your 170YYEDT (EmissionsDivisionTransmission) carb is not original to your 73. I know that the 170s are from 76 and on. Here's my source for decoding:
recarbco.com
Not that it necessarily matters for performance, but it sounds like you understandably want to keep the vehicle in original condition.
You might contact these guys for parts, as well:
Carbs unlimited
I've never dealt with them for parts, but have had good experience with rebuild kits. You WILL need the carb number to order from them.
Good luck-
-Todd