What type of rod? Push rod or connecting rod? Also, it is a salvage 94 engine that my brother used for about 3 years in his capri, it is sound. I wouldn't worry about the doubling of torque in the Z, as almost the entire driveline will be new. The rod through the firewall I guess is a concern, but it is going to be a stock engine that wont be abused. It is for the street, I dont plan to push it hard enough to throw anything. But if there is a weak flywheel bolt or two I am not sure how hard I would have to push. It just makes me uneasy that is all.
I am lucky though that the last bolt stripped, we got almost all of the bolts to 80 ft/lb with only 1/4" bite, if we had acctually run the engine with that much, I think the flywheel would of come off for sure.