If you're driving that many miles you really ought to consider doing this! My grandfather had a Olds 98 with the Diesel Chevy. He keeps incredible detail fuel records for all of his vehicles. That thing averaged 30mpg over the entire lifetime of his ownership, just like you say. Just freaking incredible...In the next year I will put 30,000 miles on, hopefully the engine will hold together. If it dose not I may put my spare 350 diesel in and enjoy 30 MPG.
And for the few complaints he had about it, the only ones that are worth fixing were stretching headbolts (occasionally blew headgaskets) and it used a tiny little gasoline fuel filter that clogged constantly. Other than that he seemed to have absolutely no problems and he drove it everywhere.
Can't be any worse than the HT, right? :suspense:
Nice looking car! Don't sweat the engine if you take care of it, plenty of them still running around just fine.