A few words of caution.
The Vanagon is OLD, so every system in the van is OLD. Rubber parts wear out, hoses, seals, bushings, etc. Plastic parts do the same. Not saying they can't be reliable, but unless all of those parts were maintained/replaced you may have to do it. Even a van 10 yeas newer is still 10 YEARS newer!
While I think a Vanagon with a swapped engine is cool, its not ideal either. First off, nearly nothing in the Bentley manual will apply anymore. The Subaru engine is better, but still not perfect. If/when it has an issue it will be difficult to find a mechanic to work on it. It would be one thing to have a swapped van if YOU could do he the work or had a good local guy willing to do it, but traveling with it might prove more challenging! Can't just roll into any VW shop, independent or factory! Many will refuse to work on it! (I've had several swapped cars)
Even the forum experts might not be able to help as much as they could with a factory set up. Simply fewer people running swaps, and not every swap is created equal. People put in different year/model engines into different year/model vans. Lots of variables in swaps. (Donor car options, year, model, recipient car options, yer model. Swap components used, etc)