back in the 70s all i ever used were rope seals 289s 390 never had a leak.the first y blocks i rebuilt i used rope and never had any leaks on any engine.to this day if i could buy good rope seals i would use them.i trust them over the rubber seals.ive taken apart 56 engines with close to 100,000 on them original motors that were not leaking.back when an easy fix for leaking seals was to force a steel shim over the top half and just replace the bottom half.not many had the tool for doing this.i would like to see a picture of one.

NOS rope seals were likely then made with asbestos. While it has been banned for health reasons there isn't really any viable substitute. The modern replacement "green" rope type seals don't work very well. So, the Neoprene type seems to be the practical work around.

some leaks are the pan gasket and seal retainer. i find the best gaskets are way better  for leaks in the rear seal aria oil will drip and appear to be the rear seal