My never ending project '69 firebird continues. So far, I stripped to bare metal and primed with SPI epoxy. I lightly blocked that to see where I needed body filler. I applied body filler and blocked that out. I recoated with epoxy and then several coats of SPI 2K urethane (that was probably done in 2014). Did I mention that it was a never ending project? I recently started body work again after all of my mechanical work and shake down runs were done. I started blocking the 2k and still have a few high/low spots here and there, but for the most part things are looking good. I still have over 1/2 gallon of 2K on the shelf. could I use several coats of this to fill the low spots before blocking again, or should I just go to a high build primer?