From everything I've learned (I've read lots about this), the internals of the likes of Autotech are fine in principle, but the fact they then have to be installed into your existing pump adds a variable into the equation. If the install isn't perfect for whatever reason, the pump can be prone to failure. I think I've read that the APR and Loba pumps are built in ridiculously clinical conditions, to exacting standards. This ensures their reliability.
So, R5. What are your plans for rebuilding your current pump with these internals? DIY? I'm not knocking your ability, and I know you're handy with a spanner. But look at the risk to reward ratio. The risk is relatively high, especially considering the VIS internals don't appear any way proven. They're more of an unknown than even Autotech. Worst case scenario is that it fails, screws the follower, knackers the cam, and you're looking at a very poorly car and a big bill. The reward, is a saving of 150 quid or so.
I've got to agree with MC71 here. If you're willing to pay 350 quid, just be patient until you can add another 150 to that and get a proven solution.
The advice against these internals as a whole (facebook + this forum) is overwhelming. You really shouldn't ignore that.