Pricing formula

Hi

We have unit of measure conversion requirement from GALLON to EACH.

As per standard UOM conversions, 1 GALLON = 3.785 LITER. We also have item specific conversions from LITER to EACH. When an item is entered in sales order, the conversion value should be calculated to EACH. For example take item A001, which has primary UOM as EACH and inter-class conversion as 1 LITER = 0.001 EACH. When this item is entered in sales order, a surcharge of $300 (this is a constant value)*UOM converted value (1 EACH = 1/0.001/3.785, which comes to 264.2 GALLON) should apply automatically.

Inter-class conversion is item-specific. So the approach we thought was to define a formula with 2 steps - step 1 is a modifier value and step 2 is GET CUSTOM PRICE. Modifier value in step 1 is amount of $300. Is this approach correct? Formula can return the calculated UOM converted value or it requires other attributes like price list line etc.?