Don't get mislead by the $1500. Article is 11 years old. The laws of physics have not changed so the results are still valid, but many parts' prices are considerably higher now. So count on $2k minimum..with good shopping AND if you can get that level of head flow in your garage.
And that is with NOTHING being done in this article to the bottom end...what are the odds of getting a 30 year old engine with rings and bores good enough to support 400 HP? If it worked at all, it would likely wear out quickly. Ka-ching.....more $$ for the bottom end. Looks as if they just ran it on the dyno, not in a car for many miles....not what most folks do with an engine! "It was great on the dyno, and is an even better coffee table stand!" LOL
The one big challenge is that getting 215 cfm flow from a start of 135 cfm flow in the intake ports from a home porting job could be tough, unless you have done it before. So I feel the 'get a grinder and learn how to use it' statement a bit much....I just can't say how much comes from the porting and how much from the valves, Serdi cuts, etc.
And, there is a lot more to this build than is said; I bet some careful work went into the assembly. I seriously doubt this was just a 'throw these parts together' build. Still, 350-400 HP for $3k would be a pretty decent return.