Here is an alien "completion" (changed the rules), probably I spent more time on this than the puzzle deserved. And it still requires a p41 glider stream, and I did not find a way to combine it with a known p41 glider gun from CGoL.
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#C [[ GRID THEME MCell ]]
x = 149, y = 111, rule = R3,C0,S10-19,30-39,50-59,75-79,135-144,155-164,175-184,200-204,260-269,280-289,300-309,325-329,385-394,405-414,425-434,450-454,510-519,530-539,550-559,575-579,635-644,655-664,675-684,700-704,760-769,780-789,800-809,825-829,885-894,905-914,925-934,950-954,1010-1019,1030-1039,1050-1059,1075-1079,1135-1144,1155-1164,1175-1184,1200-1204,1260-1269,1280-1289,1300-1309,1325-1329,1385-1394,1405-1414,1425-1434,1450-1454,1510-1519,1530-1539,1550-1559,1575-1579,1635-1644,1655-1664,1675-1684,1700-1704,1760-1769,1780-1789,1800-1809,1825-1829,1885-1894,1905-1914,1925-1934,1950-1954,2010-2019,2030-2039,2050-2059,2075-2079,B15-19,35-39,55-59,75-79,140-144,160-164,180-181,183-184,200-204,265-269,285-289,305-309,325-329,390-394,410-414,430-434,450-454,515-519,535-539,555-559,575-579,640-644,660-664,680-684,700-704,765-769,785-789,805-809,825-829,890-894,910-914,930-934,950-954,1015-1019,1035-1039,1055-1059,1075-1079,1140-1144,1160-1164,1180-1184,1200-1204,1265-1269,1285-1289,1305-1309,1325-1329,1390-1394,1410-1414,1430-1434,1450-1454,1515-1519,1535-1539,1555-1559,1575-1579,1640-1644,1660-1664,1680-1684,1700-1704,1765-1769,1785-1789,1805-1809,1825-1829,1890-1894,1910-1914,1930-1934,1950-1954,2015-2019,2035-2039,2055-2059,2075-2079,NW7D007D017D007D007D0000007D007D00190519007D010005000500017D00190519007D007D0000007D007D007D017D007D
34bo$32b3o$31bo$16b2o13b2o$17bo$17bobo$18b2o2$28bo$27bobo$28b2o$28bo3$
39bo$5b2o24b2o7b2o$6bo24bo7b2o$4bo27b3o$2b4o11bob2o13bo$bo14b3ob2obo$o
2b3o9bo4bob3o$b2o2bo10b3obo4bo$3b2o12bob2ob3o$3bo8bo7b2obo$4bo6b2o37bo
$b3o7bobo37bo$bo5b2o15bo24b3o$8bo14bobo$5b3o15b2o$5bo$146b3o$67bo6b2o
70bobo$48b2o15b3o6b2o70bobo$47bobo14bo$21b3o24bo15b2o$21bo37bobo10bo$
22bo37b2o11bo5b2o$49bob2o7bo12bo5b2o$48b3ob2obo12b3obob2o$47bo4bob3o
11b7obo$48b3obo4bo9b2ob2obob2o$49bob2ob3o10b3o$38bo13b2obo9b2o2bo$38b
3o24b6ob2o$32b2o7bo26b6o$31b2o7b2o28b3o$33bo44b2o$78bobo$78bo$44bo$43b
2o$43bobo$44bo2$53b2o$53bobo$55bo33bo$40b2o13b2o31b2o$41bo46bobo$38b3o
$38bo7$98b3o$98bo$99bo8$109b2o$108b2o$110bo8$119b2o$119bobo$119bo8$
130bo$129b2o$129bobo9$139b3o$139bo$140bo!