Can you make single length irons using conventional heads and weights?
No you really cannot make a single length set of irons from a conventional set of iron heads. Generally with most irons you would be able to adjust the lie angles so that they are all the same. Getting the clubheads to all the same weight is the hard part. If we assume the set is being assembled to a 7 iron length with steel shaft at 37.5″ and the 7 iron clubhead weight is 268 grams we need to get all the other clubhead weights to 268 grams. If the PW weights 291 grams you would need to remove 23 grams of weight from the PW to get it down to 268 grams. If you were assembling a 3 iron and the clubhead weight of the 3 iron is 240 grams you would need to add 28 grams to the clubhead to get the weight up to 268 grams. Getting the clubheads to the same weight in a good manner is the hard part.