Conversion Styles/Shrouds Heads I'll Think of something
The first time I ever heard about the Type IV (4) conversion was on the Shop Talk Forums, I think. It seemed like a good idea but I was still working on restoring my car at the time. So I didn't have the time or the resources at the time. I had also rebuilt engine already. Once my car was rebuilt and I had been driving it about 6 months, the bearings started to go bad in the engine, I didn't crack the case so they were old ones. This prompted me to start looking into the conversion more seriously. So I bought Joe Cali's Conversion Book and started to gather the parts that were needed.
Type 4 (T4) motors came in 411 & 412's, late busses, and 914's. If you can get one out of a 914 or 411/412, do it, they had less weight to push around so would possibly be in better shape. The smallest was a 1700cc and the biggest was 2000cc, and all were bigger than the biggest Type 1 (T1) motor. Originally they were in a pancake style configuration, opposed to the upright style of the bug motors.
Some other reasons why they are better than T1's are that they have a factory oil filter, bigger oil cooler, everything is beefier on the inside, you don't have to remove the heads to replace the pushrods or their seals, and it bolts right up to the transmission, if you have the proper flywheel. Those are just a few reasons that you might want to convert.
Along with the good there are some bad things. From what I have heard and read the heads have a tendency to drop the valve seats. When you are rebuilding they should be able to fix this problem. Another thing is that since they are not as popular, the parts will be harder to find and more expensive than T1 parts.
Overall this conversion is, in my opinion, the best one. It is the simplest, probably one of the cheapest to do, and not many people will be able to spot it being a different engine that was in there originally. If this doesn't get you considering this conversion you need to look at the rest of my site. And for more info on certain parts check out the links at the top.
When I think of more info I'll add it here.