$ Building a Slant 6 for performance

I appreciate the /6 for what it is, one of the most durable engines ever & guys on here do some really cool stuff with them. However, I've come to realize that it takes a lot of money having someone else do the machine work necessary to get a /6 much more HP. Shaving the head, if not the block too raising the compression, & putting in oversize valves. Besides your usual bolt on mods, like a 4 barrel, Offy or Clifford Header etc. Unless you Super/Turbocharge.
Not that re-sale value should be a very top priority in this hobby but it's good to realize if you decide to go V-8 after you've spent $1,000+?? or more on the /6, it's still probably not likely to fetch $200. Fewer interested buyers=lower demand= lower price. Sure, you could show some receipts, but it's still a hard sell. There is kind of a stigma attached unfortunately. For example you could start at 220 HP with a 90s Magnum 318 (for about $300 around here) and go up from there HP wise, instead of spending a ton of money on the six. However you would have to get a 318 727 trans, and 8 1/4 or expensive 8 3/4 rear end. That's probably $600-$1,000 maybe. A few trade offs. To each his own. My 198 /6 is still stock at this point, I've picked up on great info thanks to this great forum.