308H blocks with 308 on the side should really be worth far more than those with HP. The vast majority of HP cast 308's are really only suitable for a HT Brougham as these were the only cars to get 308 at the start of HT. Not long after the 308 was made available across the range (close to the end of HT) the cast mark changed to 308. So for most HT and HG GTS with 308, the "correct" engine is a 308H with 308 cast mark. It's only a month or so of HT GTS production where the 308 cars got HP blocks.