Seating it one caliber (.38") into the case and starting at the minimum load and working up should be fine. Don't get so lost in the #s that you lose sight of the "forest". It should look right.
The manual will state which bullet type they used to get that oal. You should have more than one manual for cross-reference that will increase your chances of finding an example of exactly what you're loading. Also, additional manuals help solve discrepencies in data. One of my manuals listed .44 magnum max loads that were just a hair over the STARTING load in a different manual. (LEE 1st ed. vs SPEER #13 .44 mag 300gr) I checked a third source that aligned with one of the manuals (didn't help). The truth in my gun was about in the middle of the two based on chronograph data. I solved this discrepancy by starting with a load that was mid-range in one manual, but below starting in the second and worked up slow.
Why didn't I be super safe and use the starting load from the most conservative manual? Well, it was a judgment call, but I had already loaded other bullet weights in the same brand case with the same powder and shot them in the same gun, so I was working with known entities except the new bullet weight. The range from starting in the conservative manual to max in the other was huge. If it was a new gun, different powder, whatever, I would have used the most conservative start point.
Good luck and have fun. Handloading is addictive! I just started to save $$, but I enjoy it as a hobby on it's own.