The 88 is basically a hunting rifle and the caliber should be suited to the game. As for values, the books show the .243 going about $50-100 more than the .308 in similar condition. .358 and .284 are worth more.
The pre-64s bring a premium and carbines run more than rifles. The 88 does not have much collector interest, and never really caught on, with production of about 284,000.
Top prices are $600 for .308 pre-64 and $700 for the .243. For the post-64, the figures are $500 and $550. Carbines bring $700 for each caliber. Those are 100% or NIB retail prices.