Get the aftermarket rods and get the peace of mind. I'm also currently acquiring parts to build up another engine for my supra and have tossed up the same idea many times myself. I rather build a motor that can take a lot more power than what my goals are. This way, i know that as long as i'm maintaining it properly, i can drive it hard as often as i want and not have to worry about the motor itself. Just as long as it's tuned properly.
I believe that you should build it strong and right to begin with, then all you have to do is add mods (leaving a certain reasonable safety margin), 'til you had enough, are broke, or scared of driving it.
One thing people don't realize is that the money they spend on all the external mods is more than enough to build a very strong motor, then grow from there. You can change mods anytime you want, but you can't just get in there and make your motor stronger, whenever you need, unless you have a shop at your disposal.
Start with a stock supra for example....
Cost of downpipe and full exhaust gets you a set of forged pistons.
Cost of electronic boost controller gets you arp hardware
Cost of good IC kit, and BOV gets you crower type rods pretty much.
and bunch of other examples like this. Leave the clutch and the rest as is.
Everything you can do at home, even the clutch if funds are tight, wait 'til later. You can call a few friends and swap your clutch when you're at that point.
The car won't be very fast after this, but u'd be surprised how much faster and stronger it'll pull compared to stock.
At this point, you KNOW you have a strong engine. Then you spend the time to build it slowly as money becomes available. It'll take you less time, money, and effort to achieve big numbers than taking a stock engine with 120k miles and trying to get in the Guinness book of records. You'll always be patching something up and not enjoying the car itself.
2JZ put high HP stock because the stock platform is a seriously built motor. I wish MKIII guys would begin there as well. Then we'd have nothing to envy.
Sorry for the book, but got a little bored :biglaugh: