Anytime someone changes valve train geometry etc, the springs IMO should be changed. The stockers were not meant for anything other than stock rockers. Many have had success and failures by not changing them. Safest route is to change them. L76/LS9 springs are great and low cost for what you suggest.
At the same time the retainers get changed to LS retainers to work with the upgraded springs. Locks are not a requirement or suggested item unless you go above 110# springs.
If you are looking for the best power for the money spent on rockers with an NA, aim for the ER rockers. Being a split ratio they do the best job overall.
