Type 4 motors are very nice indeed, but will end up costing you a lot in the end. Comparing a 2L stock type 4 and a stock 2L type 1 motor, the type 4 would come out on top. if you have a large budget, building a 2.7L type 4 with over 300 horsepower is easy, and you'll get tons of reliability. but this isn't really necessary in a daily street car. I would go with a New or Rebuilt type 1 case. the type 1 parts are much easier to source and cheaper as well. Depending on what you want (high reving screamer, or torque motor) will depend on the specs...you obviously know this
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I'd go with the type 1 motor, just because of ease of fitment, lighter weight in the rear, and parts are easy to come by. there are also a lot of locals that have large displacement type 1 motors where they have tried and tested some of the best highperformance, or long lasting products out there.
good luck with everything.
Stephan