what you need to remember is that you need to get the technic up to level 40 then share the others (being strike range and armour) up to level 80 for the 450 for example
strike lvl 17
range lvl 17
technic lvl 30
armour lvl 17
megid is a cheap way to lvl up technic
carline is a cheap way to lvl up armour
weapon discs is the best way to lvl up range and strike it takes a few hours good luck shy dragon

found a way to do 450 by level 30
to level 10 using megid for technic proline for armour and any of the ash for range, strike and technic
get armour to 2 with proline, get technic to 4 with megid and then use an ash to get strike to 2, range to 2 and technic to 6, thus going from 9 to 12.

now get armour to 4 with proline, then use an ash to get strike to 4, range to 4 and technic to 8, thus going to 20.

now get armour to 6 with proline, get technic to 10 with megid and the use an ash to get stirke to 6, range to 6 and technic to 12, thus to level 30 and you should now have made a model 450.

after that you can use whatever you like to get the levels higher it will stay at model 450 i beefed up its defence but it is up to you