well, easy to compare, at first, then when you tack on the price of high hp driveshafts, it's not so cheap anymore.
Even a 250whp B series can break the stock driveshaft on repeated drag runs. The only reason it doesn't happen so often is because more often that not, we get wheelspin than driveshaft twisting torque.
The K series pose a few problems, and that is mainly cost.
I dunno, but I'd like A/C on a daily driver, and with the K engine costing more than 20K, plonking it into a near stock chassis I think it's not a great idea, esp. if there is the word 'limited' budget.
With 20K, you can get a great handling B16B with a lot of drivetrain mods, like chassis stiffening, polybushes, good suspension, etc.
You need to get a couple of things from various models to come up with a daily driven K series in an EG, with a/c and p/steering.
If not daily driven I think very possible to do cheap, since we can omit a lot of extraneous stuff like climate control, etc. etc, and we can use aftermarket meters rather than retaining the stock EG dash, which brings a lot of costs down in terms of getting/modding harness, etc.
But I'm sure you already checked out how much a stage 3 driveshaft costs, right, so I guess when you compare the cost, the B-series is a lot cheaper when you target big horsepower, and also purchase related equipment to handle that kind of power.
I'd look forward to seeing how you manage the power, because 250 and up whp on a front wheel drive doesn't actually 'want' to go straight, because of various issues like LCA and chassis flex. Suspension tuning becomes critical then, and so is chassis reinforcement.
For us, a K-series is very expensive, while for mat salleh, a USDM K-series with vtec (not the crippled K20A3) is damn near the price of a JDM B18C and it's related parts. And best of all, they can pass smog easily.
But when you talk about potential wise, yeah, the K series can probably generate a lot more horsepower, but for less cash? I don't think so.
For a dedicated drag vehicle, I think the K is the next big thing, for daily drivers, people here rather buy new car for the status symbol.