It really isn't safe or even possible to turn grips on a long blank with a wood lathe unless you have a way to support both ends and several points along the length. I would turn the grip on a mandrel to final shape then glue it to the blank.
What do you consider long?
Having never seen a Renzetti or Pacbay except in pictures it looks like sewing machine motors but what do I know.
This question Dana posted is loaded. Simply because we all have ideas/methods that work for us and it's kind of like bellybuttons ... most of us have one. I can see this as being a long-winded reply with my interpretation of the solutions.
I have done lots of demos and turned on that lathe at Woodcraft and I can't stand the fact you can't adjust the speed except via belt changes.
First recommendation would be to add a Variable Speed Motor and PSI has one for around a $100. Invaluable in my opinion.
I have three lathes (working on getting a 18x47) fourth this year because I'm making platters, bowls and boxes because SWMBO likes them and because she like them it is easier to get the tools necessary for this to happen when she supports my hobbies.
One is a 7 x 14 Cummins that I haven't turned on in a couple three years because I can't get that mini metal lathe to not cut a 0.006 taper in 3". I also have my very first 7x14 $50 wood lathe that has MT1 tapers that will eventually be the base for my baginski beveler.
I have a 10x18 wood lathe (and a bed extension that's never been out of the box) and have done 2 piece 9' rods with no problems. Steady rests are simple to make that are adjustable down to the smallest area by offsetting/stagger the wheels so they overlap themselves.
Most have posted pics of a 4-Jaw self-centering Wood Chucks which will not get small enough because at the closed position there is still a nice sized hole. These are great for turning inserts/pens but poor for handles on blanks.
Most chucks that size are unnecessary for rodbuilding. For the Rikon a MT2 Micro 3-Jaw self centering chuck would work just fine for this 2" Chuck
and with a 20% coupon you're looking at $28.
There's this nice sized hole through the headstock and you can simply pass the rod blank through the headstock.
Over the last year and a half I've picked up some what I consider jewels in the "tips" departments via emails.
1 - Kevin Proctor posted about using K&S Stainless tubing from ACE for mandrels and of course I have 4 ACE's and none of them carry it.
I did find thick walled SS316 on Amazon that was cheap ($10) and I bought a 3' piece and covered the cost by selling 1/4" mandrels (with a $10 1/4" MT2 Round Collet) to our pen turners who keep buying these pieces of crap mild steel that bends easily.
2 - Randy Ruwe on using masking tape as a counter balance to eliminate whip or wobble in the tip end of the blank on short lathe beds due to lack of support of that portion of the tip that extends beyond your roller support. (anyone interested in this I'll be happy to post the long reply because it is simple and it works).
3 - Roger Wilson? posted on another forum about using these fiberglass driveway markers for those of you that live in snow country. Simply cut off a chunk and turn the end down to a taper so it fits inside the blank and then use a Live Center.
While Harry's method (gotten a lot of ideas from him) is great for butt ends that are solid like bamboo, I'm skeptical of using this method on a plastic rod blank because I'm paranoid.
4 - Koos has been kind enough to exchange emails with me and give me a ton of ideas. Here's a pic of his setup (Koos if I shouldn't have posted this I apologize) that should spark some interest especially on the steady rest. I used Inline Roller Skate Wheels I got free from the the local store that installs new wheels on these things and tosses the old ones away. These urethane wheels make great steady rests.
Now that I'm 95% percent back from my knee surgery and the crushed hand I did a couple of years ago I can play on the lathe at extended periods of time except for when it hovers around 0º - 20º in the garage.