ALWAYS follow the instructions. They wrote the instructions for a reason, and that reason is usually to be sure you use the produce correctly.
You know, you could simply tumble lube a few bullets android them as-is and SEE if there is any problem chambering. I find that as-cast bullets are more accurate. I have been casting since about 1975, and haven't sized a bullet since about 1976.
Next, what is the actual measured throat diameter and groove diameter of your gun? Without those, you have no idea if 0.454" is correct.
If .45 Colt, the cylinder's throats should be 0.4555-0.4595" and groove diameter should be 0.450-0.454". You want the bullet to a tight slip fit in the cylinder's throats and at least 0.001" larger than actual groove diameter.
The case OD should be 0.474-0.480", but it needs to fit the chamber which is 0.4862-0.4902", so there could be lots of slop and the oversized section of the bullet, even if seating doesn't swage it down at all (and it will), may still fit.
I mean, what does it really cost to load a couple of inert dummy rounds, which you should do anyway, and verify if the as-cast bullets will work?