Barrel can get Scope grooves.
1400 barrel fits with the same Transfer port sealing arrangement but the seal needs to be fashioned to fit the valve or vice versa as the 1400 seal is flat both ends and uses a seal guide on the ID to take the load.
The current breeech and barrel arrangements if a thread bushing is made . Barrel support from a Disco for current offerrings or QB to use the .562 barrel from a 1400.
The distance from the back screw to the Breech screw is the same for the SSP250, 150, 140, 1400, 130, 1300 and all the current single shot guns as well. That makes barrel options nearly endless.
Valve can get HOT(high Output tune). There are 1400 barrels on 150's that do over 600 fps. at 10" figure 525 Max. There are HW barrels and LW barrels on every American gun you can name. A lot of them have Venom shrouds and Gen II brakes.
So yes. any barrel you can show a machinist can be profiled and cut from a modern blank and made more accurate as the Crosman tubes often left a lot of accuracy on the table.
Custom Airgunsmithing is only limited to your imagination if you have the budget. If it is something we do on a regular basis there will be some economies of scale to save you on the bottom line but one offs to your print is where the costs start to skyRocket. Paying a $100 Surface refinsihing because you have 4 lbs of stuff and the price would cover 150 lbs of steel. Minimuns for every finishing of your parts will kill you at the anodiser, media blaster, oxide shop, heat treat, surface grinding ect.
150, 400 and 180 have the same valve but do not share barrels as the 180 & 400 were the only relatives in that branch of the Crosman Family.