With the valvespring technologies there are right now,you could go alot more than 4 to 5 runs on springs..

Know with a 358 inch motor,that would be harder on springs,because the rpms.The best HP making spring right know is the PAC pro stock double spring,but it is a 15 run and out spring..but you cant beat the PSI spring for the price.I had 30 runs on a set of manley nextex with 950 lift going thru the lights at 9300 and shifting at 9000...and they were fine when checked..