Chevy LS springs are another good option.
I am not convinced that the 4.2 pushrods are correct. Little known fact but there are actually 3 different pushrod lengths that were offered by Jeep. Another consideration is whether the base circle of your cam is machined differently then a factory grind. That alone would dictate a different length pushrod. To be safe I would do a bit more research and even incur the expense of a pushrod length measuring tool to make sure you are setting the engine up correctly. http://www.summitracing.com/search/p...pushrod%20tool
or your machine shop may be able to help.
Don`t forget the break in oil and proper cam break in procedure. The use of Brad Penn or Joe Gibbs ZDDP fortified oils will help ensure your engine runs long and stays healthy.