International Shipping for items over 150 lbs

I am a new zenner. I have to say I am so impressed with what Zen Cart can do, and the help that is found on this forum.

I posted this in the wrong thread last night. I hope I have put it in the right place this morning...

We have a business that sells automotive tire parts. Some our heavy items (150+ lbs) and some normal weight (UPS and USPS handle these). In addition, we offer free shipping for continental US for cart over $500.

** So here is what I have done so far, last point is my issue:**

• Use UPS module for Continental US (via geo_zone) for normal weight items under $500 -- figured out the geo_zone from past threads :laugh:...
• Use Order Total/Shipping (ot_shipping) set to Free Shipping for National on everything over $500 for again Continental US
• Use USPS for International shipping for things under 150 lbs, again coded based on geo_zone (Non-Continental US)
• :wacko:International shipping for items over 150 lbs. These items have shipping calculated into the cost up to any US port. I will add verbage to this shipping method to communicate that it is the customers responsibility to use their carriers of choice to move the product from a US port to the final destination. We will also help with this, but most will use their own.
  What I wanted to do is use a modified freeoptions module to flag those products that have a weight over 150 lbs and also going international. What I need to change is the coding that allows this module to show up with other modules. I have looked at all the other modules and freeoptions gives me the parameters I need. My only issue is the fact that it comes up with other shipping modules.

Can somebody help me? Am I overcomplicating?? Is there an easier way or module??...please help...I am eager to learn and tired of this piece of the puzzle.

Thank you in advance
Sandy