Well.. to build a strong, reliable LS-VTEC motor, one really ought to reinforce the bottom end and freshen the motor overall. So if the chassis and interior are in satisfactory condition, then 100K isn't necessarily excessive mileage.

Just as general advice, I'd recommend a compression and leakdown test for the car you are looking to purchase. Also, plug in "LS-VTEC" into our search engine...from the reults you can get a feel for what's involved in making a "Frankenstein" B18B run strong and reliably.