There's nothing wrong with OGTS's 2.0 litre engines. But you can easily modify a 1.9 into a 2.0 litre. If aftermarket forged pistons are used, and early (pre-1974) connecting rods utilized, they are nearly bulletproof. ALL the European 2.0 litre engines used the later cast steel connecting rods (as used on most of the 1974 and all of the 1975 Opel 1.9's in the US), versus the earlier forged steel Opel rods used on 1.5, 1.7, and 1.9 litre engines through 1973. A true Euro 2.0 litre has a 95 mm bore, which is 2 mm larger or roughly .080" more than a 1.9 litre. For an Americanized 2.0 litre made from a 1.9 block, we normally bore the block to 3.75", or 95.25 mm, which is .090" more than the stock 93 mm bore of a 1.9. Sounds like a lot of machining, but the Opel block can handle it, it's only .045" per side. I've only rejected one block as unsuitable for such an overbore due to core shift.
Bob