Tampering with smog equipment is an EPA (federal) issue. A non-compliant engine (1j) would fall into that category. But it is enforced by the state (police, smog shop, etc). But if they don't look (or care to look) then theoretically, you don't have much to worry about. Besides, how many non-supra people are really going to know the difference (in look) between a 7m and a 1j, or even know a 1j was never sold in the US (not counting a smog shop or state ref)?