Here's a few tips.
Trilogy cocker pump kits have the same threading for their pump guides as the LPC/front plug on a spyder/clone/VL. There's some clearance issues on some guns, but nothing a dremel or some sanding can't fix.
Now the two keys to converting a stacked tube blowback gun are eliminating the blowback from the valve, and slotting the hammer to separate the bolt from the hammer.
To get rid of the blowback there are a few options. JB weld and reshape the valve pin to remove the flat spots on the pin. Find a valve pin with out any flat spots (don't ask me where). Or use a valve that's the same size, but for a non-blowback gun. Trilogy cocker valves are the right size. That's what I used on my pump VL.
Trilogy valve on the left, stock VL valve on the right. Palmer's makes an aftermarket trilogy valve as well.
Slotting the hammer is about 20 minutes work with a dremel and a cutting disk.
This lets the bolt cock the hammer back, and then allows the bolt to close forward.
Then just attach a pump handle to the bolt. You'll want to set it up so that it closes the bolt to the right spot. Not too far forward, not too far back. You'll probably end up playing with springs for a while too. Mine has wicked hammer bounce.
Here's mine finished.
Not quite happy with the pump rod yet.