Sure, I'd get the most rigid tubing you can find if you do go that route, you'd want it to be around .475" in overall length so it can squish and seal...
However I prefer stuff like shown below, which I made for a fellow member here. He needed 2 different lengths as one of his marauders has a taller custom breach.
It's .265" tubing slid over .196" tubing and jb welded with a lip extended out for the gaskets to ride on, same style as stock. Hillairgun has the same style that is .161", however for the cost of that you could custom make what I show below with anything between .161" and .196".
However, for an unregulated .22, opening up to .196" will drastically reduce your shot count and pressure range availability due to a larger swing in FPS as pressure drops, so you'd either tune hot for a declining string with very few shots, or a smaller bell curve than you have now but more shots than a declining string.
A .196" ported .22 cal marauder could make 60 fpe till about 2500 psi before it falls off (needed very heavy ammo for this, 30+ grains), or maintain 50 fpe until 2100 psi with 25gr+. A .161" ported .22 cal marauder would do about 50 fpe until 2400 psi and to hit 60 fpe would need all 3000 psi and would immediately taper off each shot. Hopefully that provides some insight to what porting challenges you may face ahead...
For the valve porting to able to flow the full .196" you'd have to open up the throat or reduce the stem diameter within the throat, stock is .21X~, but for .196" porting you'd want .243"~ throat diameter. The downside to this is larger throat/seat diameters require more hammer energy to open, so you'd have to increase hammer preload. The stock throat can only handle around .161" porting or so, which would work okay with hills custom transfer port...
You'd also have to modify the bolt probe to flow for .196", I am unsure for .161" as I don't recall the stock probe diameter.
What I would do is...over complicated so don't ask me! LOL
View attachment 488488 -Matt