I see that Melling offers a Standard Replacement, a High Volume, and a High Pressure oil pump for the 302 Ford. Not sure what is different about the high pressure and high volume ones...
Which is best for a ~300 hp engine with stock oil pan?
I would go with the standard pump. The high volume can drain your pan. Plus, it takes more horsepower to turn the high volume. I think the standard will be more than enough.
I went with the high volume when i replaced mine, although yes it can run the pan low at idle, I plan on getting a larger pan in the future. If you plan on just a standard pan and light mods, stick with the stock one. Start spending money on the engine (alot), I'd go with the high volume.
Yes, it does take more energy to turn it, but I doubt anyone could really tell the difference without a dyno. hell, upgrading to a 130 3g alt will rob power from you, but what are the benefits?
I have used the Melling high volumn for years with no problems. Better protection than the standard plus it has better oil pressure which is always good. The high pressure may "wash" the bearing under normal driving and even performance situations.
If you build your small block with "loose" clearances,and/or a high performance motor go with a high volume. Tight and stock use motors--- std volume or high pressure. Now if we're talking about FE series motors, High pressure. Any Cleveland/351M/400 nothing but a high volume will do. I've been running a high volume in the 5.0 in my Ranger for two years with the stock dual sump fox-body pan and it's never run the pan dry. A high pressure pump is simply a std volume pump with a high pressure relief in it.