Not sure what mold is the closest to the OE senko but most that are available are real close.
For injecting you will need an injector, I use Basstackle.coms because it has a tip that locks on and does not fall off unless you want it to.
If you buy molds from differant companys most have a 5/8 port and are pretty much the same. Jacobs baits has a smaller hole but sells an adapter to use any that are available.
Your stick mold is worth something but it is worth kepping too. Ck the classified section.
Plastic has been gone over and you can search for LONG discusions on it. Your choice is just that Yours.
All of the mold makers have great service and products so that has changed in the last 2 years as there is more makers out there. I did mention one and you may not know him but he and Bob work together so if you look for Bobs look to Basstakle.com. Others include Bears baits,Dels, Jacobs baits and Caney Creek is the newest one to help us out. Good Luck Frank