What goodies do I need to build a Fast slant 6

Hi 12many
Yes I hear you 15k is a lot for a 6 that has basically no technology advancements just all old school, and yes I’d thought about a V8 but I have a V8 engineered into my Toyota 4Runner so just wanted to go with a six cylinder with a real lumpy cam setup I had hoped it wasn’t much stuffing around to put a 265 in it as they can make a heap of power pretty cheaply but I’ve had a few tell me that it’s also a bit of stuffing around!, and at 50yo I’m past the stuffing around stage in life been there and done the and the body’s just to broken and tired so was hoping now that the 225 was able to make some reasonable power gains but just didn’t realise How expensive they are to make power.
I’m open to suggestions still at this stage as it’s just sitting there and hence why I’m on here trying to figure out how to go about it.
Cheers
I’ll be brief, my take is purely from the perspective of being a V-8 person and only having a slant 6 at the time and trying to up its performance when I should of just bit the bullet at the time and gone with a swap. Sounds like you’re up for the challenge and rewards of a built Slant:)